Organic Farmer - February/March 2019 by JCS Marketing, Inc.

February/March 2019 Mating Disruption in California Specialty Crops Use of Biological Soil Amendments in Organic Agriculture and Food Safety Risks Testing the Value of Soil Tests? Weed Control in Organic Cool-Season Vegetable Production

PUBLICATION

Volume 2 : Issue 1

Navel Orangeworm Control!

Mating disruption product for conventional and organic California nuts!!

Decrease Damage Increase Profit

• Up to 50% - 80% potential reduction in damage vs. current insecticide programs • Season-long control through post-harvest • Easy application with ready-to-use carrier pack

INCORPORATED INSECT PHEROMONE & KAIROMONE SYSTEMS

Your Edge – And Ours – Is Knowledge.

MATING DISRUPTION PRODUCT FOR NAVEL ORANGEWORM IN ALMONDS, PISTACHIOS & WALNUTS

Organic Farmer

February/March 2019

Contact your local supplier and order now!

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Made in the USA

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PUBLISHER: Jason Scott Email: jason@jcsmarketinginc.com EDITOR: Kathy Coatney ASSOCIATE EDITOR: Cecilia Parsons Email: article@jcsmarketinginc.com PRODUCTION: design@jcsmarketinginc.com Phone: 559.352.4456 Fax: 559.472.3113 Web: www.organicfarmingmag.com

IN THIS ISSUE

Mating Disruption in California Specialty Crops

6 12

CONTRIBUTING WRITERS & INDUSTRY SUPPORT Justin Duncan

Sustainable Agriculture Specialist in the Southwest Regional Office of the National Center for Appropriate Technology (NCAT)

Use of Biological Soil Amendments in Organic Agriculture and Food Safety Risks

Neal Kinsey

Testing the Value of Soil Tests?

Weed Control in Organic Cool-Season Vegetable Production

Alda F. A. Pires

Dept. Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis Pires, Jessica Shade, The Organic Center

President of Kinsey Agricultural Services Richard Smith Vegetable Crop and KonradMathesius Weed Science Farm Agronomy Advisor, Monterey Advisor, University County of California Cooperative Emily J. Symmes Extension (UCCE) PhD, Sacramento Sacramento, Solano, Valley Area and Yolo counties, Integrated Pest Mark Lundy, Management UC Cooperative Advisor,University Extension Specialist of California Cooperative Extension and Statewide IPM Program

UC COOPERATIVE EXTENSION ADVISORY BOARD

Cover Crops That can Take the Heat

Emily J. Symmes

Steven Koike

Kris Tollerup

County Director and UCCE IPM Advisor, UCCE Pomology Farm Sacramento Valley Advisor, Tulare/Kings County Director, TriCal Diagnostics

Low-input Wheat Trials Work to Improve Understanding of Heritage Grains

Kevin Day

February/March 2019

UCCE Integrated Pest Management Advisor, Parlier, CA

The articles, research, industry updates, company profiles, and advertisements in this publication are the professional opinions of writers and advertisers. Organic Farmer does not assume any responsibility for the opinions given in the publication.

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NEW MD TECHNOLOGY AND PRODUCTS INTRODUCED IN 2018 – HOW DID THEY FARE? Nut growers today are increasingly finding that good winter sanitation and chemical applications alone are no longer enough to combat the growing spread of navel orangeworm. As a result, greater numbers of growers now are using mating disruption to increase their success in warding off the pest as part of an integrated pest management strategy. Two new mating disruption products developed and manufactured by insect monitoring and control company Trécé — CIDETRAK® NOW MESO for almonds and pistachios, and CIDETRAK® CMDA + NOW MESO for walnuts – entered the market in 2018 and already are drawing positive reviews from nut growers and pest control advisers. Trécé developed the products in its own laboratory, then finetuned and field-tested the two solutions in collaboration with researchers from the University of California, Davis and USDA’s Agricultural Vince Chebny, Lab R&D Manager for Trécé Research Service, for maximum effectiveness. “We saw excellent results across the board,” said Brad Higbee, Trécé’s Director of Field Research. “Growers and PCAs were pleased with every aspect of the products, ease of application, and reduction in both trap capture and damage.”

and dramatically reduces the number of multiple-mated females by more than half. Correspondingly, the data shows a 50-80% reduction in damage compared to grower standard insecticide programs in trials where there was a difference. CIDETRAK® CMDA + NOW MESO for walnuts is equally effective. A unique combination of codling moth (CM) pheromone and a patented male and female behavior modifying kairomone (DA) as well as NOW pheromone allows growers to disrupt codling moth males and females and NOW males.

“The navel orangeworm seems to be expanding its range and density in different areas.” — Dirk Ulrich, almond grower/consultant

“More and more researchers are endorsing the benefits of mating disruption,” Higbee said. “Growers and PCAs are also praising the effectiveness of both products and now consider them an essential part of a complete pest management program.” Dirk Ulrich, an almond grower, research PCA and CCA used CIDETRAK® NOW MESO on a test plot in 2018 and was surprised to discover he had higher pressure than he anticipated before trial initiation.

According to Higbee, CIDETRAK® NOW MESO for almonds and pistachios significantly increases the number of unmated NOW females

“We saw excellent results across the board. Growers and PCAs were pleased with every aspect of the products, ease of application, and reduction in both trap capture and damage.”

7.90%

3.70% 2.90%

— Brad Higbee, Director of Field Research for Trécé Source: Dirk Ulrich, 2018

Organic Farmer

February/March 2019

Another Trécé product engineered for walnuts, CIDETRAK® CMDA + NOW MESO, addresses the double threat of infestation that occurs when nuts damaged by codling moths serve as a breeding site for navel orangeworm. Research has demonstrated that pear ester DA and CM and NOW pheromones in a CIDETRAK® CMDA + NOW MESO dispenser significantly reduces mating and walnut nut damage from codling moth and navel orangeworm. CIDETRAK® CMDA + NOW MESO, which uses two dispensers, one for each moth, are hung together on one hanger and placed 20 per acre at mid-canopy. The dispensers are easy to hang and labor efficient. Hanging them together has demonstrated more than 95 percent disruption and reduction in male moth capture in pheromone traps for codling moth and navel orangeworm.

Brad Higbee, Director of Field Research for Trécé and Dirk Ulrich, almond grower/consultant

“The navel orangeworm seems to be expanding its range and density in different areas,” Ulrich said. “I had an area on one ranch that I farm that has been pretty low pressure. I’ve never really had damage, and I’ve never really sprayed for NOW, but this year, I encountered much more pressure and I had more damage than ever before.” According to Ulrich, NOW damage has been climbing steadily, rising from less than 1 percent in 2015 to 1 percent in 2016 and then more than doubling to 2.2 percent in 2017. “In fact, I used the grower standard with and without CIDETRAK NOW MESO compared to the grower standard insecticide program alone. This consisted of three hull-split sprays timed appropriately. The damage was 7.9% in the grower standard, 3.7% or about 53% less in the grower standard plus CIDETRAK® NOW MESO and 2.9% or about a 63% reduction in the CIDETRAK® NOW MESO alone. Very impressive performance to say the least, even though, I had put it on later than I would normally, due to the late registration!”

“I really liked the simplicity that Trécé built into the uniquely packaged/RTU application system that allowed for fast and accurate application at the very low rate of 20 per acre. My rate of application was around 4 acres per manhour.” — Dirk Ulrich, almond grower/consultant “Moreover, I really liked the simplicity that Trécé built into the uniquely packaged/RTU application system that allowed for fast and accurate application at the very low rate of 20 per acre. My rate of application was around 4 acres per manhour. The packaging allowed me to open what I needed, which on a large scale will allow for greater inventory management and checking field utilization and labor use.” Ulrich will be using NOW MESO in 2019. “I’m planning on using it on larger acreage. Great product! I plan to recommend it to my growers this season!”

Codling moth is different with each generation. First-generation larvae cause the nutlets to drop from the tree under certain conditions. Nuts attacked by larvae of the second and third generations remain on the trees. Feeding damage to the kernel leaves them unmarketable and they are also a breeding site for NOW, which may result in 8-12 or more surviving NOW larvae vs. one CM larvae. Second-generation larvae frequently enter through the side of the husk where the two nuts touch. After the shell hardens, the larvae enter the nuts through the soft tissue at the stem. Codling moth not only damages the nut, but it provides a breeding site for NOW. This makes it vital to prevent codling moth damage. Monitoring continuously with pheromone/kairomone based traps, establishing and tracking degree days, checking canopies for damage and calculating the level of infestation is necessary season long for best results.

CIDETRAK NOW MESO applied in pistachio orchard

Rich French, distributer with Bear River Supply used CIDETRAK® CMDA + NOW MESO last year and said, “It’s a good tool in the toolbox, and we will be using it again this year.” Programs that have used CIDETRAK® CMDA + NOW MESO or CIDETRAK® NOW MESO alone or in combination with insecticide sprays have been found to be very effective. There is an immediate need to protect your harvest from NOW. Left un-treated, the economic damage on growers will be devastating. The time to act is now. The need is immediate. Trécé is a leading innovator in mating disruption and control systems, for both conventional and organic use.

INCORPORATED INSECT PHEROMONE & KAIROMONE SYSTEMS

February/March 2019

Trécé Incorporated 7569 Highway 28 West Adair, Ok 74330 USA

www.organicfarmermag.com

Tel: 1-866-785-1313 Fax: 1-918-785-3063 custserv@trece.com www.trece.com

Mating Disruption in California Specialty Crops By: Emily J. Symmes, PhD | Sacramento Valley Area Integrated Pest Management Advisor |University of California Cooperative Extension and Statewide IPM Program

Photo courtesy of Pacific Biocontrol Corporation.

Organic Farmer

February/March 2019

rganic producers are well aware of the crop production and protection challenges they face relative to their “conventional” counterparts. With these challenges, however, come great opportunities for exploration, development, and adoption of cutting-edge technologies. In recent years, there has been a great surge in the research and development of pest management alternatives to traditional synthetic chemical approaches. Regulation and consumer demand for organic and sustainable food and fiber has led industry to increase focus on biorational pesticides and other effective tactics for reducing pest populations and crop damage. Among those are the use of semiochemicals to impact normal behaviors of insect pests. Semiochemical is a broad term used for chemical substances used for communication. Pheromones are a specific subset of these that mediate communication among individuals of the same species. Particular insect species may communicate using a wide range of pheromone signaling, including aggregation, trail, marking, alarm, and sex pheromones. For example, if you’ve ever observed ants traveling along a very specific path, this is a behavior mediated by a trail pheromone. One of the most widely used categories of pheromones used for monitoring and population suppression of crop-destructive insects are sex pheromones. Sex pheromones can be used by insects at all levels of the mating process (long- and short-distance mate location, courtship behaviors, partner acceptance, and the ultimate act of copulation).

course be achieved by completely blocking mating all together. However, efficacy may also be achieved by delaying mating, reducing multiple matings, or causing an asynchrony in the mating behavior of males and females— all which can lead to a significant reduction in the overall numbers of subsequent generation offspring.

“Blanketing” The Environment In practice, the way we achieve mating disruption in an agricultural setting is by “blanketing” the environment with synthetic pheromone to confuse the gender of the target species that responds to the sex pheromones. For the majority of insect species targeted for mating disruption in agricultural systems, females of the species are the producers and emitters of sex pheromones and males are the responders. This confusion, and ultimate disruption, of sexual communication in insects is thought to be achieved by the following broad types of behavioral mechanisms: • Competitive attraction (false-plume-following), in which males are diverted from orienting to females because they are attracted to competing ‘false’ trails emitted by synthetic pheromone dispensers. • Non-competitive mechanisms, whereby exposure to

Continued on Page 8

Mating Disruption Mating disruption is an integrated pest management (IPM) technique that has shown significant success and promise for a number of crop-destructive insect pests. Some examples of these in California cropping systems include: codling moth (apples, pears, and walnuts); oriental fruit moth (peaches, nectarines); tomato pinworm (tomatoes); pink bollworm (cotton); omnivorous leafroller (vineyards); navel orangeworm (almonds, pistachios, walnuts, fig); vine mealybug (grapes); European grapevine moth (grapes); California red scale (citrus); peach twig borer (apricot, peach, plum, prune); light brown apple moth (berries); as well as stored product pests (such as Indian meal moth). In some cases (e.g., pink bollworm and European grapevine moth), mating disruption has been used as part of large, regional-scale, multi-agency coordinated approaches involving a number of different management tactics, resulting in declared eradication of these pests from large geographic areas. In most of these examples however, mating disruption is used as part of an overall IPM approach to pest suppression on more localized scales (i.e., individual grower blocks, ranches, area-wide cooperatives).

Continued on Page 8

Fundamentally, mating disruption acts to obstruct the pheromone-mediated sexual communication between individuals, ultimately resulting in fewer offspring in the subsequent generation. The reduction of subsequent offspring, and thus efficacy of mating disruption, can of

February/March 2019

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tion and reduction in male moth capture in pheromone traps for moth and navel orangeworm.

Codling moth is different with each generation. First-generation l cause the nutlets to drop from the tree under certain conditions. N Continued from Page 7 attacked by larvae of the second and third generations remain on based on a pheromone-impregnated synthetic pheromone inhibits or blocks trees. Feeding damage to the kernel leaves them unmarketable and Brad Higbee, Director of Field Research for Trécé and Dirk Ulrich, almond grower/consultant core sandwiched between films the ability of males to sense and/ arewith also a breeding site for NOW, which may result in 8-12 or mor permeable membranes to regulate or respond normally to pheromone surviving NOW larvae vs. one CM larvae. “The navel orangeworm seems to be expanding its range and density pheromone release (Photo 1). Others emitted from females. These include in different areas,” Ulrich said. “I had an area onare onemade ranchofthat I farm or plasticSecond-generation larvae frequently enter through the side of the polymercamouflage, desensitization (i.e., that has been pretty low pressure. I’ve never really had damage, and I’veimpregnated based materials, again where the two nuts touch. After the shell hardens, the larvae enter adaptation and habituation), and never really sprayed for NOW, but this year, I encountered much more with pheromone, and designed nuts through the soft tissue at the stem. sensory imbalance. pressure and I had more damage than ever before. ” a particular matrix to allow with Codling moth not only damages the nut, but it provides a breedin the slow,steadily, even release • Combinations ofNOW these damage mechanisms. According to Ulrich, has been climbing rising of molecules for NOW. This makes it vital to prevent codling moth damage. 2).then Hand-applied dispensers from less than 1 percent in 2015 to 1 percent in (Photo 2016 and more are considered passive, in thatMonitoring they Technologies and in Products continuously with pheromone/kairomone based traps than doubling to 2.2 percent 2017. Photo 1. Hand-applied pheromone mating provide a slow, constant release establishing and tracking degree days, checking canopies for dam dispenser for vine mealybug in grape. “InThere fact, Iare used the grower standard with and without CIDETRAK NOW of pheromone over the entire and 24- calculatingdisruption a number of technologies the level of infestation is necessary season long for Photo Credit: University of California Statewide MESO comparedavailable to the grower standard insecticide alone. This hour program period for the duration of the and products for getting IPM Program. results. consisted of three sprays timed appropriately. wasthese types season. The damage density of pheromone intohull-split the target cropping of dispensers needed for mating 7.9% in the grower standard, 3.7% or about 53% less in the grower stansystem for mating disruption purposes. depends on the cropping dard CIDETRAK® MESO and 2.9% disruption or about a 63% reduction In plus general, these are NOW often classified system, target species, and other on the delivery in based the CIDETRAK® NOWmechanism. MESO alone. Very impressive performance ecological and normally, operational factors. often think of though, three common to We say the least, even I had put it on later than I would Early in the development of passive broad (1) hand-applied due to thecategories: late registration!” (passive) dispensers, (2) aerosol (active) dispensers, rates were typically in the 100s (300 to 400 per acre was not dispensers, and (3) microencapsulated uncommon). Some advances have “I(sprayable) really formulations. liked the simplicity that Trécé been made in delivery mechanisms built into the uniquely targeting certain insect species, Hand-applied dispensers come in a packaged/RTU whereby effective mating disruption variety of forms. Some of these are

application system that allowed for fast and accurate application at the very low rate of 20 per acre. My rate of application was around 4 acres per manhour.” — Dirk Ulrich, almond grower/consultant

“Moreover, I really liked the simplicity that Trécé built into the uniquely packaged/RTU application system that allowed for fast and accurate application at the very low rate of 20 per acre. My rate of application was around 4 acres per manhour. The packaging allowed me to open what I needed, which on a large scale will allow for greater inventory management and checking field utilization and labor use.” Ulrich will be using NOW MESO in 2019. “I’m planning on using it on larger acreage. Great product! I plan to recommend it to my growers this season!”

CIDETRAK NOW MESO applied in pistachio orchard

Photo 2. Hand-applied pheromone mating disruption dispenser for navel orangeworm in Rich French, distributer withCredit: Bear Trècè, RiverInc. Supply used CIDETRAK pistachio. Photo

CMDA + NOW MESO last year and said, “It’s a good tool in the t box, and we will be using it again this year.”

Programs that have used CIDETRAK® CMDA + NOW MESO or TRAK® NOW MESO alone or in combination with insecticide spr have been found to be very effective.

There is an immediate need to protect your harvest from NOW. L un-treated, the economic damage on growers will be devastating. time to act is now. The need is immediate.

Trécé is a leading innovator in mating disruption and control syst for both conventional and organic use.

INCORPORATED INSECT PHEROMONE & KAIROMONE SYSTEMS

Trécé Incorporated 7569 Highway 28 West Adair, Ok 74330 USA

Photo 3. Aerosol mating disruption dispenser for codling moth in walnut. Photo Credit: Pacific Biocontrol Corporation.

Organic Farmer

February/March 2019

Tel: 1-866-78 Fax: 1-918-7 custserv@tre www.trece.c

We often think of three comon broad categories: 1. hand-applied (passive) dispensers 2. aerosol (active) dispensers 3. microencapsulated (sprayable) formulations

can be achieved with much lower densities of passive dispensers (20 per acre for some pests and products). Again, the rate per acre will depend on the particular pest, product, and area to be treated. There are some fun versions of hand-applied formulations as well—one product can be “shot” into the tree canopy, another “splatted” onto the crop. Aerosol dispensers (Photo 3, see page 8) are considered active dispensers, in that pheromones are pressurized and emitted in metered “bursts.” The dispensers can be programmed to release pheromone only during the period of the day or night in which the target pest is sexually active (typically at night for moth pests). Further technological advancements have allowed remote-sensing of monitoring data (i.e., trap numbers) to be coupled with variable rate delivery. In other words, during periods of the year when trap catches are high (or more pests are active), a higher rate of pheromone is released from the canister. In tree crops in California, aerosol products are typically deployed at rates of 1 to 2 per acre, with increased densities around orchard edges or perimeters of mating disruption areas, and are designed to last season-long. Sprayable (microencapsulated)

formulations are not as common as hand-applied and aerosol dispensers, although there are some products available. A great benefit of sprayable mating disruption is that it is a technology that growers are familiar with in terms of the application method—it can be put directly in the spray tank and, in most cases, applied like any agrichemical. One of the challenges with sprayable formulations is stability of the material within the capsule from which it is designed to be released slowly over a period of a few to several weeks. Weather conditions, particularly excessive heat during summer months, can impact the longevity of these materials. In most cases, sprayable pheromone formulations require multiple applications during the season for most target pest species to achieve best efficacy. There are many benefits to using mating disruption as part of an overall IPM strategy to suppress pest numbers and reduce damage, one of which is, of course, availability for use in organic systems. It is important to remember that not all mating disruptant products are registered for organic use. Always check product labels and discuss the use of any materials with your organic certifier. Continued on Page 10

February/March 2019

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Continued from Page 9

Naval Orangeworm Control!

Mating disruption product for conventional and organic California tree nuts!!

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“Set it and Forget it” Other benefits include the “set it and forget it” aspect of the hand-applied or aerosol dispensers. Once deployed, they will remain active season-long, allowing you to focus other pest management efforts more specifically to other pests you may encounter in the system. Over the course of multiple seasons, population suppression using mating disruption has been shown to be compounding year after year, resulting in overall long-term reductions in pest pressure from a given species. In addition, issues common to conventional pesticide applications are mitigated or avoided, including resistance development and secondary pest outbreaks. Mating disruption is highly specific to the target pest, providing protection for non-target species such as pollinators and natural enemies (which can then be relied upon more heavily to provide biological control for a range of pests in the system). Remember, like any pest management tactic, mating disruption is not a panacea, and is certainly not a replacement for critical cultural practices that should be employed in tandem to reduce pest numbers (for example, orchard sanitation for navel orangeworm). There are several important technological, biological, ecological, and operational factors to consider when adopting mating disruption and evaluating its efficacy. For example, mating disruption successes are often greatest when employed over large treatment areas, particularly if the target pest is highly mobile. Size and shape of the treated area can impact efficacy, as can overall pest pressure. Mating disruption as a stand-alone in most systems is most impactful at low to moderate pest densities. At higher pest pressure, supplemental treatments or management tactics of some kind may be needed, especially in the early years of employing mating disruption. Monitoring within mating disruption treated areas using pheromonebased traps may be difficult (as pheromone traps are often “shut down” or zeroed out as a result of the male confusion). Alternative monitoring strategies to detect pests and evaluate population pressures may need to be employed.

MATING DISRUPTION PRODUCT FOR NAVEL ORANGEWORM IN ALMONDS, PISTACHIOS & WALNUTS

• Up to 80% or more potential reduction in damage vs. current insecticide program • Season-long control through post-harvest • Easy application with ready-to-use carrier pack • No moving parts, no batteries, no gummy deposits • Removal not required

There is a wealth of information available to you as you explore adopting a new technology such as mating disruption. Your local University of California Cooperative Extension farm and IPM advisors will be able to discuss with you best practices for success, as can your pest control advisers/crop consultants, and technical representatives from the mating disruptant manufacturer.

Contact your local supplier and order now! Visit our website: www.trece.com or call: 1-866-785-1313 ®

INCORPORATED INSECT PHEROMONE & KAIROMONE SYSTEMS

Organic Farmer

Your Edge – And Ours – Is Knowledge. February/March 2019

Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com

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Use of Biological Soil Amendments in Organic Agriculture and Food Safety Risks By: Alda F. A. Pires | Dept. Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis and Jessica Shade | The Organic Center

Organic Agriculture and Increase of Demand

rganic farming in the U.S. has been growing rapidly, with over 20,000 certified organic operations in the U.S. (United States Department of Agriculture (USDA)/Agricultural Marketing Service (AMS), 2016): a 300 percent increase in domestic certified organic operations since 2002. Organic food sales have increased by 8.4 percent over the last year, blowing past the stagnant 0.6 percent growth rate in the overall food market to reach annual sales in excess of $7.6 billion in 2016 (USDA-AMS, 2017). Organic food now accounts for more than five percent of total food sales in the U.S., and demand for organic products continues to outpace production (Finley et al., 2018).

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Currently, 83 percent of families in the United States have bought organic products one or more times in the past two years, and 90 percent of parents report that they choose organic food for their children at least sometimes (OTA, 2017). This growing demand for organic products is based on consumer trust in the organic label, and the perceived guarantee of quality, safety, and sustainably of organically produced food (Finley et al., 2018).

Use of BSAOAOs and Food Safety Risks Organic agriculture is one of the most strictly regulated agricultural systems, with a rigorously-enforced list of practices by which organic producers adhere. USDA’s National Organic Program (NOP) prohibits organic

February/March 2019

farmers from using synthetic fertilizer (USDA-AMS, 2000). Instead, they often use biological soil amendments of animal origin (BSAAOs) to replenish soil nutrients, enhance water retention and infiltration, increase soil permeability, increase drainage and areration, and improve soil structure (Rosen and Bierman, 2005; Rosen and Allan, 2007). Raw manure (uncomposted and untreated animal manure) is a type of BSAAO that is used in many crop-based systems, but is particularly important to certified organic farmers because of the ban on synthetic fertilizer (USDA-AMS, 2000). Unfortunately, crops that are grown in soils amended with raw livestock manure can become contaminated by microbial pathogens carried by raw manure

such as E. coli O157:H7, Salmonella spp., Campylobacter spp., Listeria monocytogenes and Cryptosporidium parvum. Fresh produce presents a unique food safety challenge due to the absence of a kill step between harvest and consumption. The prevention of microbial contamination of crops has been based on time-interval criteria between the application and crop harvesting (Olaimat and Holley, 2012). It is crucial that raw manure application, compost processing and application practices be adequate to reduce the risk of potential crop contamination.

Mitigations Strategies to Reduce Food Safety Risks in Soils Amended with BSAAOs The Food Safety Modernization Act (FSMA), Produce Safety Rule, Subpart F, defines a BSAAO as “untreated” if it has not been processed to adequately reduce microorganisms of public health significance (Food and Drug Administration (FDA), 2015). Untreated BSAAOs consists of animal manure (e.g., raw manure, aged, staked, slurries, animal bedding, agricultural tea made from raw manure) or nonfecal animal byproducts (e.g., bones, offal or feathers), which were not submitted to a valid controlled physical (e.g., heat) or chemical process (e.g., high alkaline pH), biological process (e.g., composting) or combination of processes (FDA, 2015). The rule requires that untreated BSAAOs must be handled, conveyed, and stored in a manner that does not contact covered produce during application and minimizes the potential for contact with covered produce after application (FDA, 2015). However, FSMA does not

All photos courtesy of Alda Pires.

currently specify safe time-intervals between the application of untreated manure and crop harvesting.

produce, that is not compatible with most organic cropping cycles (LGMA, 2016).

Current USDA’s National Organic Program (NOP) standards, on the other hand, do specify wait-times, and require that untreated animal manure be applied at least 120 days or 90 days prior to crop harvest, depending on whether the edible portions come into direct (e.g., carrots, radishes, lettuce) or indirect contact (e.g., peppers, tomatoes) with the manure-amended soil (USDA-NOP, 2011; FDA, 2015). The Leafy Green Marketing Agreement (LGMA) requires a 12-month waiting period between raw manure or grazing animals in a field to produce fresh

While the FDA did not specify timeintervals in the current FSMA rule, they have previously proposed a 9-month minimum interval requirement, and are reserving a final decision on the wait time between application of raw manure and produce harvest until more data is collected and a risk assessment is completed (FDA, 2015). The nutrient and microbiological characteristics of animal-based soil amendments (i.e., untreated livestock manure) depend on several factors such as livestock species (e.g., cattle,

Continued on Page 14

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Continued from Page 13 poultry, small ruminants and swine), production system, animal diet, bedding material (amount and type), manure management (e.g., storage, application rate), pathogen itself, and type of manure (e.g., solid slurry or liquid) (Harris et al., 2013). In addition, once the soil amendment is applied other factors may play a role on survival, such as soil properties (e.g., type of soil, composition, temperature, moisture), culture management (e.g., irrigation type, crop type, cover crop, previous use of the land) and environmental conditions (e.g., season, ambient temperature, rainfall, humidity, sunlight) (Hutchison et al., 2005; Harris et al., 2013). These factors may be directly related to the type of livestock production and agricultural practices, which vary between regions and states. A recent multi-regional study

conducted by University of California (UC) Davis and collaborators on current practices of organic farmers regarding BSAAOs reported that while some organic farmers use raw manure, in particular small-scale farms, the majority of fresh organic produce farmers primarily use compost as their major soil amendment (Pires et al., 2018). Manure management practices (e.g., sources, storage, type of treatment, application method, application time, etc.) may affect the survival and persistence of pathogens in amended soils. Therefore, mitigation practices to decrease the risk of potential microbial contamination to fresh produce crops resulting from application of untreated manure must take into account the multiple farming factors (e.g., agricultural and livestock practices) and specific characteristics of the region such as environmental factors, geological factors, growing seasons

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(year-round versus seasonal) that may be involved (Pires et al., 2018). Controlled and managed composting processes have been shown to suitably reduce the populations of foodborne pathogens to minimal levels (Bernal et al., 2009; Moral et al., 2009). The United States Department of Agriculture/ National Organic Program requires that compost is produced through a process in which the initial C:N ratio is between 25:1 and 40:1 and maintained at temperature between 131°F and 170°F for 3 days using an in-vessel or static aerated pile systems, or for 15 days using a windrow with a minimum of five times turning (USDA-NOP, 2011). The same composting parameters are required in Produce Safety Rule (PSR) of the Food Safety Modernization Act (FDA, 2015). FSMA PSR provides these two examples of scientifically valid, controlled biological treatment (composting) but other treatment processes validated that have been proven to meet the microbicidal standards are acceptable (FDA, 2015).

Conclusion Prevention of pre-harvest contamination of fresh produce is critical for the safety of consumers, and a top concern of farmers regardless of farming system. Best practices can be employed to reduce microbial concentration in manure and preventive control of cross-contamination during farming and harvesting of fresh produce, but more research is necessary to expand our knowledge on the efficacy of current practices and more extension is needed to transfer this information to farmers.

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Research must identify the multitude of factors influencing pathogen survival in pre-harvest produce production environments on soil amended with BSAAOs. We must also develop risk mitigation strategies for reducing fresh produce microbial contamination in systems using BSAAOs. The FDA is conducting a risk assessment and, in

Continued on Page 16

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manures and chemical criteria for compost maturity assessment. A review. Bioresource technology 100, 5444-5453. FDA, 2015. Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption. Food and Drug Administration. Final Rule. In: Federal Register Notice (Ed.), 74547-74568. Finley, L., Chappell, M.J., Thiers, P., Moore, J.R., 2018. Does organic farming present greater opportunities for employment and community development than conventional farming? A survey-based investigation in California and Washington. Agroecol Sust Food 42, 552-572.

Continued from Page 14 collaboration with the U.S. Department of Agriculture and other stakeholders, is undertaking critical research to provide scientific support for appropriate time interval(s) between application of raw manure and harvest of fresh produce. Research on organic systems examining the intersection of BSAAO use and pathogen presence and survival is especially critical, because organic farmers are frequent users of BSAAOs. Additionally, pathogen ability to colonize and persist on organic soils may differ from their conventionally managed counterparts, because on average organic soils have higher soil organic matter, more nutrient availability, improved structure, and increased biodiversity (Mader et al., 2002; Marriott and Wander, 2006). To ensure the high-quality of organic products are maintained, we must conduct science-based assessments of current organic practices related to raw manure use and to identify potential food safety risks, which will benefit organic growers and their consumers. Meanwhile, until more data is collected, the Produce Safety Rule of the Food Safety Modernization Act does not interfere with the National Organic Program standards.

References: Bernal, M.P., Alburquerque, J.A., Moral, R., 2009. Composting of animal

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Harris, L.J., Berry, E.D., Blessington, T., Erickson, M., Jay-Russell, M., Jiang, X.P., Killinger, K., Michel, F.C., Millner, P., Schneider, K., Sharma, M., Suslow, T.V., Wang, L.X., Worobo, R.W., 2013. A Framework for Developing Research Protocols for Evaluation of Microbial Hazards and Controls during Production That Pertain to the Application of Untreated Soil Amendments of Animal Origin on Land Used To Grow Produce That May Be Consumed Raw. Journal of Food Protection 76, 1062-1084. Harrison, J.A., Gaskin, J.W., Harrison, M.A., Cannon, J.L., Boyer, R.R., Zehnder, G.W., 2013. Survey of food safety practices on small to mediumsized farms and in farmers markets. J Food Prot 76, 1989-1993. Hutchison, M.L., Walters, L.D., Avery, S.M., Munro, F., Moore, A., 2005. Analyses of livestock production, waste storage, and pathogen levels and prevalences in farm manures. Applied and environmental microbiology 71, 1231-1236. LGMA, 2016. Commodity specific food safety safety guidelines for the production and harvest of lettuce and leafy greens. Mader, P., Fliessbach, A., Dubois, D., Gunst, L., Fried, P., Niggli, U., 2002. Soil fertility and biodiversity in organic

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farming. Science (New York, N.Y.) 296, 1694-1697. Marriott, E.E., Wander, M.M., 2006. Total and Labile Soil Organic Matter in Organic and Conventional Farming Systems. Soil Science Society of America Journal 70, 950-959. Moral, R., Paredes, C., Bustamante, M.A., Marhuenda-Egea, F., Bernal, M.P., 2009. Utilisation of manure composts by high-value crops: safety and environmental challenges. Bioresource technology 100, 5454-5460. Olaimat, A.N., Holley, R.A., 2012. Factors influencing the microbial safety of fresh produce: a review. Food Microbiol 32, 1-19. OTA, 2017. 2017 U.S. Families’ Organic Attitudes and Behaviors Study. Organic Trade Association. Pires, A.F.A., Millner, P.A., Baron, J., Jay-Russell, M.T., 2018. Assessment of Current Practices of Organic Farmers Regarding Biological Soil Amendments of Animal Origin in a Multi-regional US Study. Food Protection Trends 38, 347-362. Rosen, C.J., Allan, D.L., 2007. Exploring the benefits of organic nutrient sources for crop production and soil quality. Horttechnology 17, 422-430. Rosen, C.J., Bierman, P.M., 2005. Using Manure and Compost as Nutrient Sources for Vegetable Crops. in Nutrient Management for Fruit & Vegetable Crop Production. University of Minnesota. USDA-AMS, 2000. National Organic Program, Final Rule. In: Department of Agriculture, A.M.S. (Ed.), 1-50. USDA-AMS, 2017. United States Department of Agriculture, Agricultural Marketing Service, Organic Integrity Database. USDA-NOP, 2011. Soil fertility and crop nutrient management practice standard. . In: Program, N.O. (Ed.), Fed. Reg 7, Subtitle B, Chapter I, Subchapter M, Part 205. 400-401.

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Testing the Value of Soil Tests? By: Neal Kinsey | President of Kinsey Agricultural Services

ow much value do farmers and growers place in the use of soil tests? Based on responses to this question, many organic farmers, gardeners and other types of growers say they do not rely on soil tests at all. How do such attitudes come to be? Is it possible that a soil test could provide information that is truly helpful to those who intend to grow organically? If so, how can that be determined in a way that adds confidence and assurance rather than causing mistrust and doubt? How can you manage what you cannot measure? Does growing crops organically have to be based on the assumption that because they are produced without poisons they must automatically contain the highest available nutrient values as well? How is it possible to provide top nutrition from depleted soils just by stopping the use of chemicals? Compost can help to supply many nutrients, some of which may not even presently be measured. The same can be true from the use of kelp, humates, pulverized oyster shells or sea shells, rock or clay dusts or other broad spectrum types of natural materials. But can what these materials contain be expected to supply all of what the various types of soil in the world need to grow the most nutritious organic crops?

Adding Materials Far too many involved with organic food and feed production assume that when it comes to soils for growing the most nutritious food or feed that you can just keep on adding and adding materials for building nutrients because such applications only help to improve the soil for growing better plants. But the truth is, every time you apply too much of one nutrient to the land, it will affect the availability of other nutrients in that soil, and any excess of one or more nutrient elements will eventually result in deficiencies of one or more of the other needed elements that help determine the nutritive value of what is to be grown there. The only way to know what a soil truly needs is to measure what is there and to understand what is required for a balanced uptake of all elements the plants need for survival and production.

Common Assumptions There is a common assumption that is made in regard to what plants need in order to grow best. Many will insist that some plants require very acid (low pH) soils to grow, while other crops require basic (high pH) soils to grow best. In fact, some plants can survive in very low pH soils and others in very high pH soils (so if you do not know the correct

Fertility levels will differ greatly in various parts of this field, and accordingly, so will the nutrient value of the crops produced from each area. All photos courtesy of Neal Kinsey.

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nutrient requirements for the soil in which to grow that crop, then plant them in soils with a pH they can best tolerate) but both types of plants will actually do their best in the same soils where all other food and feed crops also grow best, which is a soil that contains an acceptable percentage of each nutrient to be considered as “balanced” for top production and excellent nutrient value. Such soils can be identified in a number of ways once corrected. But the greater question is, if a soil does not already have the right mix of nutrients, what must be done to achieve what is right? Most farmers and growers will readily point out that their soils are quite different from other soils when considering whether to test and fertilize them. But some of those same farmers and growers will apply the same amount of compost to several truly different soils without knowing the nutrient levels in the soil or in the compost and assume it will always be for the good. Is it actually possible to tell what is needed and what is not?

So then why not start by at least considering who can correctly tell you the answers to something you already know? Take a sample from a good friable soil, mix it thoroughly and divide it into three or more parts. Do the same for an obviously weaker area in the same field. Label them so you know which is which, but so as not to identify the good one from the bad one (or as some have done in testing us, call the good soils bad, and the bad soils good). Send each part as a soil sample for analysis to different laboratories. When the results come back, expect to have three completely different sets of numbers on the soil tests for both the good and the bad areas. Furthermore, if it has been requested that recommendations be made by the testing laboratory and the same crop and yield has been listed for both the good and the bad parts, too often, the exact same recommendation is made for both of them. This is especially true for nitrogen, phosphate and potassium. When this happens, then most likely

the recommendation is based on the stated desired yield, not the actual soil analysis.

Test Your Soil Test Test your soil test in this way first. Then considering all of the differences between the test numbers, which set of tests should be chosen to use as the base for the application of soil amendments, limestone or fertilizer materials? Now it is time to test your advisor or consultant. Too often the one there to give advice actually cannot even read the soil test because so many different farmers are using so many different labs, and consequently the fertilizer representative does not understand what the numbers are actually showing. (One field man who had worked selling fertilizer for over 25 years admitted he had never understood soil testing until after attending several training classes conducted by our company on how to understand the tests being advocated for use by those in his company).

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Interpreting the Numbers In seeking answers to such questions, it is best to consider first things first, because with so many different types of soil testing methods and reports, it can be confusing as to what is being indicated as needed by each test for each different soil. Can it be determined whether or not the answers recorded on a soil test are actually providing the information an organic grower needs to know? Consider that even with the most accurate soil test, someone has to interpret what the numbers mean. How is it possible to tell who knows what they are talking about and who does not? For growers who intend to grow highly nutritious (nutrient dense) foods, these are crucial considerations that need to be correctly answered. For those concerned about the true value of whatever crop their soil is producing, there are ways to help verify the efficacy of the advice being given by others before deciding what should be done to best help that land. In fact, there are a number of ways to determine which test or tests can be useful and the value of the information that is provided by those who strive to interpret what should be done to the land based on the use of soil tests.

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Certified organic cilantro. Same field, different soils, same fertilizer program.

Continued from Page 19 Be sure to keep in mind that these comments are not intended to say or even to imply that the soil tests from soil testing laboratories are not correctly determined. So long as the lab can arrive at the same answers time after time, then the soil tests are being run correctly. The real question is, once those numbers are determined is there someone who can take those numbers and apply them as they relate to soil fertility in order to obtain the best results right out in those fields that show differences in nutrient content? In regard to testing the good and the bad soil, ask whoever it is that provides the advice for fertilization based on any of those tests to identify which soil is which and why one is not as good as the other one. This is one big reason why so often those who just use a soil test to sell fertilizer will advocate that growers should feed the crop and just use a soil test to point the farmer or grower in a general direction. Then to justify their argument some will go on to say that correcting the soil is too expensive, soil tests are not really exact enough to treat the soil based on the numbers provided, or newer tests are more scientific than those developed years ago and that makes the older testing methods used for making these types of decisions now obsolete. The best way to find out how a program works is to try it on enough land to see that the results indicate it is worthwhile. This can generally be done right on the farm by choosing an area that is large

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enough to justify economy of scale purchases in regard to lowering the costs, but small enough not to break the bank if for whatever reason it does not work (such as drought, hail, early or late frost, etc.). Experiment first, then as it becomes obvious as to the beneficial results, begin expanding as the current fertilizer budget allows. Just spend the budget on the materials that will provide the most benefits for growing organically. When testing it yourself, nobody has to take the word of someone who has never used the program and thus may or may not know the benefits of using such.

Study Nature Not Books Dr. William A. Albrecht, upon whose work this program is based, repeated many times, “Study nature, not books” in reference to who or what to believe as agricultural science. Not that he did not believe in studying books, as he likely read more than most and correctly applied the information those books provided. But his point was this, when you read one thing in a book, but see something different happening over and over as it is repeated out in the field, believe what you see is happening in the field, not the book!

Soil Balancing Soil balancing is in reality both possible and needed, and by using the correct tools, each grower can prove the truth and value of it all from actual personal experience right on the land being farmed, not from information others

February/March 2019

parrot from those who have never even been trained how to use the program correctly. When a program is worthwhile, there will be good reason as to why it works. But for those who have reason to oppose even the best of programs, there will also be sufficient excuses as to why it will not work. At age 74, and having worked using this program in field applications since 1973, not once has there been evidence that the intricacies of a program like this is correctly learned just by reading about it in a book! The Albrecht system of soil fertility is a program based on soil testing that must be learned. Like anything to be learned, it has to make enough sense to warrant the time it takes to master it, and this then requires being educated to correctly understand how it actually works. But in the end, it is only correctly learned by those who work to find out how to use the entire program properly right out in each field. Just remember, start small and then expand as the derived benefits may warrant! Neal Kinsey is owner and president of Kinsey Agricultural Services, a consulting firm that specializes in restoring and maintaining balanced soil fertility for attaining excellent yields while growing highly nutritious food and feed crops on the land. Please call 573 683-3880 or see www.kinseyag.com for more information. Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com

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Weed Control in Organic Cool-Season Vegetable Production By: Richard Smith, Vegetable Crop and Weed Science Farm Advisor, Monterey County

Introduction

rganic production has grown significantly in Monterey County in the last 25 years and in 2017 it was valued at $380 million (9 percent of total agricultural value). Nearly all large-scale vegetable production companies produce organic vegetables and most crop consultants need to be familiar with organic production issues and practices. Weeds are a very significant production and economic issue, and given the lack of organically acceptable preemergent herbicides, growers must rely on other practices that help them reduce weed pressure and make subsequent hand weeding operations more efficient and affordable. The high cost of weeding in organic production has encouraged growers to develop practices, production systems and equipment that helps them succeed. In some cases, this may entail investment into high tech equipment or to use time-tested techniques that continue to be effective and economical today. The soil seedbank is the reservoir for weed seed and the quantity of seed in the seedbank either increases or decreases depending upon practices employed in the production field. The weed control philosophy of a farming operation starts with the grower and filters down to the foremen and workers. Some operations establish a zeroweed seed tolerance philosophy that is communicated

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and adhered to throughout the organization. The philosophy simply states that no weed should be allowed to set seed. If successfully carried out, the number of weed plants that set seed in the production fields is reduced which results in less weed seeds being added to the soil seedbank and ultimately, cleaner fields. Practices such as removing any weeds before they set seed and carrying weed plants out of the fields during weeding operations for disposal elsewhere are examples of practices that foster the zero-tolerance philosophy.

Cultural Practices Cultural practices can be helpful in reducing weed pressure or avoiding weed pressure. For instance, locating crops that are particularly sensitive to weed issues in fields with less weed pressure (e.g. baby vegetables on high density 80inch beds that cannot be cultivated on the bed top) helps reduce weeding issues for that crop; also, locating crops that have better weed control systems, such as more thorough cultivation strategies (e.g. single line cauliflower on 40-inch beds), in weedier fields, helps to provide a way to avoid high hand-weeding bills. Making good use of crop rotations can reduce weed problems. For instance, some large-scale growers that grow many acres of baby vegetables will often concentrate baby vegetables on one ranch where fast maturing crops are rotated with each other. The advantage of this system is that baby vegetables, which generally mature in

Figure 1. Number of germable weed seeds per m2 of soil in 17 different vegetable production farms.

Group 1—ranches with frequent rotations to short-term baby vegetable crops; Groups 2 and 3—ranches with rotations to longer-season vegetable crops such as broccoli, peppers and leeks which allow more weeds to set seed.

30 days, mature before weeds can set seed. As a result, in these rotations, weed seed may germinate during the crop cycle, but do not have enough time to set seed before the crop is terminated which thereby draws down the number of weed seed in the soil seedbank over time (Figure 1—Group 1). By contrast, ranches where crops such as peppers, broccoli, leeks and other long-season crops which suffer from multiple waves of weed germination tend to have more weeds that set seed and deposit them in the soil seed bank (Figure 1—Groups 2&3).

Preirrigation Preirrigation prior to planting and killing the subsequent flush of germinating weeds with shallow cultivation or flaming is a key practice to reduce weed pressure for subsequent crops. The preirrigation stimulates non-dormant weed seed to germinate and, once the resulting weed plants are destroyed prior to planting, there are fewer weed seed available to infest the subsequent crop. This practice has been shown to reduce weed pressure in the subsequent crop by 50 percent. If time allows, preirrigation can be repeated, with an additional 50 percent reduction in weed pressure.

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Photo 1. High density planting of spinach. Note that crop seedlines are too close together to allow traditional cultivation on the bed top. All photos courtesy of Richard Smith.

level over the years. Crops grown in rows on 40 or 80-inch wide beds can be effectively cultivated. Standard cultivation typically leaves a 4-inch wide band around the seedline. For instance, in a lettuce crop grown in two seedlines on a 40-inch wide bed, cultivation controls the weeds on 80 percent of the bed. Some growers even use a narrower uncultivated band around the seedline to control a higher proportion of weeds on the bed. Closer cultivation can be achieved by careful visual guidance of the cultivator or using camera guided systems such as the EcoDan and Robocrop. The camera guided systems allow the tractor driver to cultivate accurately at higher speeds with less stress. The 4-inch wide band that is left by traditional cultivation is the area that is hand weeded. The expense of hand weeding depends on the number of weeds left in this zone. If weed pressure is light, hand weeding operations can be reasonably efficient and fit into the projected crop production budget. However, if weed pressure is high, then hand weeding can be expensive and put the profitability of the crop in jeopardy. In high density baby lettuce and spinach production, there is no ability to cultivate the bedtop; in this production system, the net effect of the cultural practices that we discussed above provide the level of weed control prior to the final hand weeding prior to mechanical harvest (Photo 1); as mentioned above, the expense of hand weeding will depend upon the success of the weed control practices employed prior to planting.

Photo 2. Finger weeders cultivating leeks. The action of the fingers disrupts the soil in the seedline and upends young weed seedlings.

Increasingly, the availability and cost of labor are issues that organic growers are facing. As a result, growers are considering implements that can reach into the seedline and remove weeds mechanically. The simplest equipment that can remove weeds from this zone are finger weeders (Photo 2). There are three companies that manufacture them: Buddingh (Michigan), and Kress and Steketee (manufactured in Europe and available through US distributors). These implements work best on transplanted crops because the

Continued on Page 26

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Continued from Page 24 fingers take advantage of the size difference between the transplanted crop and germinating weed seedlings. Typically, 7-10 days after transplanting the finger weeders can be run to upend young weed seedlings that are in the white thread stage (Photo 3). There is a learning curve to master the effective use of finger weeders. In general, finger weeders only remove a portion of the weeds in the seedline, and have been shown to reduce subsequent hand weeding time by 40 to 50 percent, thereby improving subsequent hand weeding efficiency. A great advantage of the finger weeder technology is that it is relatively cheap and is accessible to growers large and small. For more information go to: https://www.youtube. com/watch?v=I4kzebMG6rE .

Automated Weeders Automated weeders are now available that use a camera to detect the crop and weeds, a computer to process the images and a kill step to remove the weeds. The Steketee IC and Robovator (Photo 4) use a split knife that travels in the seedline that closes between crop plants, thereby killing weeds, and opens as it passes crop plants. The Garford machine uses a spinning blade that also travels in the seedline and spins around the keeper plants. In evaluations that we conducted, the machines removed 51 percent of the weeds in the seedline and reduced subsequent hand weeding by 37 percent. These automated weeding machines are quite expensive and are mostly utilized by larger scale operations; however, some distributors of the machines also have lease options. The bottom line is that the current technologies available for removing weeds from the seedline do not control all the weeds, but they take out a significant proportion of the weeds, thereby reducing subsequent hand weeding and make it more economical and efficient.

Photo 3. Pigweed upended by finger weeders.

Other Cultural Practices Other cultural practices that are employed by organic growers include the use of dark colored plastic mulches for crops like peppers. These mulches are effective at controlling most weed species. Problems with this technology occur where weeds emerge from the planting hole and in the furrows; in addition, yellow nutsedge can puncture through the plastic and emerge. Solarization is a process where the heat from the sun is trapped in the bed using clear plastic (http://ipm.ucanr.edu/PMG/ PESTNOTES/pn74145.html ). Soil temperatures need to be maintained at 110 to 125°F six inches deep in the soil for 4-6 weeks to kill weed seed as well as soil pathogens. This technique has used successfully in inland parts of the state, such as the Central Valley and the desert. It is particularly effective on small seed weeds and has been particularly useful in organic carrot production where hand weeding this high-density crop would be prohibitive if weed pressure was high. Flaming is another practice that can be used on crops that take a long time to germinate (e.g. carrots, pepper, leeks and cilantro); broadleaf weeds that germinate prior to the crop plants are killed by flaming and the crop plants safely emerge a

Continued on Page 28

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Table 1. Number of weeds per 3 ft2 on two evaluation dates after treatment.

Continued from Page 26 capric acids) and Axxe (ammonium nonanoate) are examples of long chain fatty acids that are registered Organic Herbicides for use on vegetables; however, currently they are mostly used to Currently available organic herbicides provide preplant burn down or spot are mostly based on fatty acids or treatments. Suppress has been used essential oils. They are non-selective, successfully in automated thinners post-emergent foliar herbicides that to remove unwanted lettuce plants disrupt membrane integrity and cause and weeds in the seedline. These leakage of cellular contents which types of materials require the use of results in bleaching and death of adjuvants that improve penetration plant tissue. Suppress (caprylic and and coverage of the material on the weeds. In addition, their efficacy is improved in warmer temperatures Photo 5. Shepherd’s purse recovering after treatment with fatty acid herbicide. and full sunlight. These materials work best on small weeds, but regrowth of the weeds occurs if the growing point of the weed is not killed (Table 1; Photo 5). These materials may prove to be useful when automated weeders that use a spray kill mechanism are developed for use in vegetable production. day or two after the flaming treatment.

There is interest in finding organically acceptable herbicides that are based on microbes or that are plant-based with different modes of action

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than described above. For example, Marrone Bio Innovations is conducting research in this area and have found natural products that show specific activity on certain weed species (e.g. Amaranthus). It is not clear at this point when these materials may ready for commercialization, but I mention it here because it is something to keep an eye on, as in the future there may be some new organic herbicides that have different modes of action which could expand their role in organic vegetable production.

In Summary In summary, weed control in organic vegetable systems uses an integrated approach managing rotations, field selection, weed seed sanitation, preirrigations and cultivation to keep weed populations at manageable levels. Hand weeding is relied upon to address weeds not controlled by these approaches. However, given limited availability and the rising expense of labor, technologies such as finger weeders and new automated weeding technologies will increase in importance. Organic herbicides currently have a limited role in providing weed control in production fields, but future innovations in organic herbicides and application technology could increase the role that they play in proving weed control in organic vegetable production fields. Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com

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Cover Crops that can Take the Heat

By: Justin Duncan, Sustainable Agriculture Specialist in the Southwest Regional Office of the National Center for Appropriate Technology (NCAT).

ne challenge of organic crop production in hot places is proper cover-crop selection and management. Which covers are most appropriate? Which can take the heat? Too many times the available answers aren’t a proper fit for hotter areas. Cover cropping is especially important in hot places because soil organic matter volatilizes at such high rates. This effect is not always obvious, because the organic matter that persists in hot soils tends to be fairly durable. As organic matter is deposited, the least durable materials, like leaves, are the first to break down. Tougher materials, such as wood, can withstand heat better and will decompose more slowly. Consequently, hot soils have already lost much of their highlyvolatile organic matter, and what remains is quite tough and resilient. On the other hand, soils in cooler areas still retain more ephemeral organic matter, which burns off quickly with temperature increases. This explains why a temperature increase of two degrees Fahrenheit will often cause a 10 percent loss of organic matter in a cool region, but only a 3 percent loss in a warmer region. The take-home point for growers in hot areas is to favor pithy and woody cover crops, because their organic matter holds up better in the soil, decomposes slowly, and will last longer. This article will discuss several candidate crops of this type. As soils lose organic matter, they also lose the ability to retain water, which contributes to warmer ambient temperatures. Since decomposition

in hot areas is so fast, it takes about twice as much input of soil organic matter to replace organic matter lost through volatilization and harvest of crops. Thus, a producer in a hot area is fighting three battles with soil organic matter, and all are uphill. First is the heat, which depletes the organic matter from the soil. Next is the sheer amount of material it takes to restore fertility to the soil each season or growing cycle. And third is maintaining enough soil moisture to retain the limited soil organic matter that is there. In no-till systems, about half as much soil organic matter is lost through decomposition as in conventional tillage. Organic matter in soil also regulates availability of different minerals necessary for plant growth. For example, the more soil organic matter, the more N (nitrogen) and C (carbon), as well as phosphorus (P) is available, and the increased microbial activity also makes potassium (K) more available. Another effect of higher soil organic matter is that it disperses minerals that can have negative effects, such as iron, by binding to them in the soil organic matter matrix. This and other metals can be toxic in higher concentrations in the soil and inhibit root growth. In acidic soils with toxic levels of manganese, organic molecules such as cysteine and tannic acids, which are readily found in plant materials, can be helpful in reducing the amounts to less harmful levels. Another highly toxic metal found in acidic soils, aluminum, has also been found to be relatively ‘disarmed’ by organic acids found in the soil. These bind enough aluminum to influence root growth significantly. Although soil organic matter (SOM)

is very important to soil health, it is harder to maintain in hotter areas. The options available for producers to build SOM are varied. They can add compost or manure, use no-till, or incorporate cover crops into the rotation and later into the soil. Cover-cropping generally makes use of non-cash crops to cover the soil in order to prevent erosion and weed build-up and to generate and regulate soil organic material. Most literature in the United States about cover crops is concerned with more temperate regions, so information about covers for hotter areas is sparse. These environments are more sub-tropical than temperate, like southern Florida, Texas or California. Areas such as these are seldom bothered by frost, so cover crops that do well in other areas, like vetch and Austrian peas, may not do as well. Instead, more-tropical cover crops can be useful in these areas because they offer longer growing seasons and provide more heat-units than are available in more temperate regions.

Considerations: Soil Performance: One must keep in mind that even if a cover crop generally performs well in your region, your specific soil type may be very different than the cover’s ideal conditions. Water: Rainfall patterns and fluctuations can determine whether or not your cover crop is successful. There have been cases when expected rains did not fall after fields were seeded, resulting in patchy germination of the cover crop. This allowed weeds to establish in the field, partially defeating the purpose

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Continued from Page 30 of the cover crop. One way to prevent this situation is to mix seed. Some covers require more moisture not only for germination, but also in the initial growth phase. Thus a mixture of seeds could be used to overcome climatic constraints or moisture limitations during initial planting. Once the cover crops have taken the moisture they need from the soil, then they conserve soil moisture through shading, acting as a living mulch as well as dew sequestration. Eventual Cover Crop End Use: Many times, cover crops are tilled under to capitalize upon the release of their nutrients back into the soil and to add organic matter that will improve tilth and soil health. Some producers opt to leave the terminated cover crop in place so they can use the residue as mulch for the following crop. Residue resilience plays a big role in the usefulness of a particular crop as a cover, because some covers are much more resistant to decomposition in hot climates than others in this regard. Growing Cycle: The cover crops discussed here are strictly for places with at least a nine- to 10-month growing season. For these cover crops to be effective, they must be able to grow unimpeded until flowering. The dangers of planting them in areas with inadequate time to grow is that they don’t persist and won’t complete their life cycle, nor will they fix the amount of nitrogen or biomass that is expected, because their lives were cut short by the weather. Legume Vs Nonlegume: Many cover crops are legumes, which means they can require a Rhizobia inoculant on the seed before planting. While the young roots are developing, the Rhizobium ‘infects’ roots by first cooperating with the plant to form infection threads. These tubules allow the rhizobia to move from the outside of the plant to the root cortex where the bacterium ‘sets up shop’ to produce nitrogen-fixing nodules. These Rhizobia are host-specific and usually require an inoculant to ensure their presence in the soil. In many cases, Rhizobia will form nodules on

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a legume outside of its host range, but the nodules will not function properly and instead of fixing nitrogen they will act as a sort of disease on the plant. Functioning nodules are almost always some shade of pink when broken open, while non-functioning nodules are grey, tan, or brown when opened. It is very important to purchase the appropriate Rhizobia to accompany legume cover seed, in order to encourage the right symbiosis to ensure crop productivity. In clover, this can mean a seven-fold increase in dry matter over the uninoculated clover. Other legumes show similar trends in production when accompanied by the appropriate Rhizobia. There are, of course, nonlegume cover crops. I personally favor legumes because the soils I have worked with required a jump start on ecological succession re-establishment (thus mimicking natural cycles) and for me the pioneer crops that get the best results are legumes because I am rotating legumes with vegetables and not establishing pasture where a mix of cover crops would be more favorable. Nodulation: Rhizobia nodulation can be negatively affected by many different factors, which in turn causes a drag on yield. This yield drag is compounded because the factors that affect nodulation usually also affect the plant in negative ways. For example, soil temperature extremes reduce nodulation because the genes that determine nodule initiation are inactivated. Soil salinity can also affect rates of nodulation. Salinity effects can differ vastly from species to species of legume and also type of rhizobium. Habitat: Another benefit of cover crops is that they can provide habitat for beneficial insects, which can use the cover crops as a rallying area to visit adjacent fields to attack their prey. For more information on this concept read the ATTRA Publications Farmscaping to Enhance Biological Control and Companion Planting & Botanical Pesticides: Concepts and Resources at www.attra.ncat.org.

February/March 2019

Weeds: Cover crops can also help suppress weeds within a crop rotation. Many cover crop species exhibit allelopathy, which is

the suppression of one plant’s growth by another plant. This can be useful in weed suppression, as with the use of ryegrass or corn gluten meal to suppress weeds, but it could be detrimental if the wrong cover crop is used, such as certain legumes with cotton. Cotton seedling emergence was depressed to 60 percent with incorporation of varying amounts of hairy vetch and crimson clover residue and there was also a 30 percent reduction in cotton yield. Nitrogen: Although they play a role in suppressing weeds, legume cover crops can increase yield for subsequent or companion crops. Legumes accumulating nitrogen for the subsequent crop is the point of growing cover crops, or at least one of the main benefits. Yield and yield components should be affected in a positive manner, and the degree to which a particular cover crop affects yield is a consideration. It’s known that legumes fix nitrogen and that other crops benefit from that nitrogen in varying ways. However, it is important to remember that each legume fixes a different amount of nitrogen and releases it at a different rate. These rates depend not only on the species of cover crop but also its stage of development. Caution: Some plants, though tremendous biomass generators, are not appropriate as cover crops due to difficulty in controlling their spread, like Aeschynomene and kudzu, which have noxious weed status.

Sub-Tropical Cover Crop Options The following table describes the traits of cover crops that are suitable for hot climates. Many of them leave more durable organic matter than common cover crops. The subsequent cover crop descriptions are only an abbreviated selection of materials from the ATTRA publication: Cover Crop Options for Hot and Humid Areas.

Crotolaria juncea (Sunn Hemp) Over the past few years we have seen a rise in popularity in the use of Sunn Hemp. It’s a versatile and useful warm season cover crop.

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Table 1. Change in the soil nutrient status after each cover crop (in ppm). Numbers are calculated by subtracting the pre cover crop soil nutrient concentration from the post cover crop nutrient concentration (Soti, Rugg, & Racelis, 2016).

Work done in a thesis by Savannah Rugg Sunn Hemp (Crotalaria juncea) was chosen as a cover crop for my thesis research in multifunctionality of cover crops in south Texas because of its ability to withstand high temperatures and humid climates. The crop was grown in two different farms with different soil types and sub climates. The first farm, Terra Preta farm in Edinburg, Texas, had great germination rate in sandy loam soil. However, with high rabbit pressures the crop was grazed and did not produce a good stand. If rabbits or other herbivores are pests on your farm, then you may consider going with a less palatable legume as a cover crop. The second plot, Yahweh Farm in Harlingen, Texas, has a clay loam soil and experiences more rainfall than the farm in Edinburg. The plant date was delayed because of heavy rainfall in May and June, so the cover crop was not seeded until July 2, 2015. Sunn Hemp did quite well on this farm and produced 4,540 pounds per acre of dry biomass. In terms of weed suppression, there was a cover crop to weed ratio of 4.58 pounds: 1 pound (dry biomass per acre), so the plot was not weed free but the cover crop did outcompete the weed competition. This could be due to the late planting date because a previous trial planted earlier in the year had a much denser stand and less weed presence in field. Sunn Hemp did very well at promoting mychorrizae spores in the soil. Compared to the control which had 50 spores/10 grams of soil Sunn Hemp had 187 spores/10 grams of soil.

Lablab

Sunn hemp

Sudan grass

Control

0.2

0.55

0.9

0.45

0.2

1852

1406.5

1427

500

3360

Copper

0.6

0.2

0.4

-0.1

-2.3

Iron

0.1

0.15

Magnesium Manganese

24 -1

35.5

13.5

-0.5

0.65

-2.45

-6.7

Nitrate

-3

7.5

0.5

OM%

0.45

0.87

1.46

1.08

-0.48

0.1

0.05

0.1

Phosphorus

9.9

19.2

19.3

15.35

6.8

Potassium

142

205.5

138.5

143

Sulfur

0.4

-14.25

-18.65

-12.8

-32.9

Zinc

0.6

0.5

0.6

0.25

-5.3

200 Number of spores/10 gm of soil

On-Farm Benefits of Sunn Hemp in Subtropical Organic Farms

Pearl Millet Boron Calcium

180 160 140 120 100 80 60 40 20 0 Control

Pearl millet

Lablab

Sudangrass Sunn hemp

Cover crop type

Figure 1: Number of mycorrhizal spores per 10 grams of soil under each cover crop. Our results indicate that the mycorrhizal spore density was influenced by the cover crop identity. Highest number of spores was found under Sunn Hemp followed by Sudan grass and lablab (Soti, Rugg, & Racelis, 2016).

Sunn Hemp resulted in highest nitrate concentration in the soil. However, contrary to our expectation, Lablab caused a decline in the soil nitrate. A possible explanation for this outcome could be the high density of weeds in the Lablab plots relative to the other treatments. Similarly, Sunn Hemp also out performed other treatments in the conservation of phosphorous in the soil signaling its potential as a warm season cover crop to improve soil health in subtropical agroecosystems. Overall Sunn Hemp performed the best to enhance soil biology and chemistry in the summer planting season in South Texas. If a farmer is trying to enhance mychorrizae density, soil organic matter, and nitrates in the soil profile, then Sunn Hemp would be a great option for a cover crop. However, if weed suppression is the main service a farmer is looking for in a cover crop they may want to try Sudan grass or ensure an earlier planting date to provide more canopy cover. Sunn Hemp has potential to be a great summer cover crop in the hot and humid climates of South Texas.

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Sunn hemp can be used as a cover crop, as well as planting in a row integrated into a cash crop to attract beneficial insects to control pests. Photo courtesy of Rex Dufour, NCAT.

Lablab purpureus (Hyacinth bean) This vine is native to Africa and has been used there and throughout Asia for many years. It is a monotypic genus, meaning that there is only one species within the genera: Lablab purpureus, formerly known as Dolichos lablab. While there is only one species, there are several sub species, landraces, and cultivars due to local adaptation. The vines can either be annuals or short-lived perennials. The leaves can be eaten raw or cooked, but the seeds must be cooked to destroy cyanogenic glycosides that can cause vomiting, shortness of breath, debilitation and convulsions. Aside from food, Hyacinth beans are an effective wildlife attractant (deer) and ornamental crop.

As a cover crop, it is quite effective smothering weeds and fixing nitrogen. Due to its initial slow growth, weeds should be controlled during its establishment. Once it starts actively growing, it is an aggressive competitor and will crowd out and shade newly emerging weeds. Once cut and dried, Lablab biomass contains around 50 pounds of nitrogen per acre. Some of the climbing types can grow to be 25 feet long, but unsupported in field conditions, they usually attain 40 inches or so in height. Although it’s a cover crop and food source for both humans and animals, it can also be very ornamental. Its flowers are quite showy, and those are followed by purple seed pods. The seeds are either white or black depending on the variety, and some of the wild types have mottled seeds. The seeds have a peculiar feature, an elongated white hilum, also known as an ‘eye”. The showy flowers attract pollinators, but the vine is subject to the same complement of insects that attack beans. Lablab prefers acidic soils of a range from pH 4.5 up to about 7. It doesn’t tolerate flooding very well and can be quite drought tolerant after establishment. It requires a minimum of about 30 inches a year of rainfall. In addition to Rhizobium, Lablab also inoculates successfully with the Vigna group of the Bradyrhizobium. Bradyrhizobium has been shown to enhance yield components of hyacinth beans, such as shoot dry weight and overall yield, without significantly influencing pod size, which means the increased yield was from a higher number of pods produced per plant. Hyacinth bean also relieves soil compaction more quickly than grasses. Lablab roots increase interconnected pore space in compacted soils three times faster than grasses like sorghum. Lablab also reduced soil ped size, although sorghum and wheat did not. This research suggests that since Lablab increased porosity and reduced ped size in compacted soil, it would also increase the infiltration rate and reduce runoff, which would also serve to hasten the compaction repair process. Lablab benefits from root associations with vesicular-arbuscular mycorrhiza,

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Continued from Page 35 especially Glomus mosseae. In field studies, G. mosseae increased dry matter, Rhizobia nodulation, and phosphorous uptake. The additional nodulation led to an enhanced uptake of nitrates (Mahdi and Atabani, 1992). Lablab requires greater amounts of heat units than crops like clover or winter peas. It should be grown in areas suitable for its production, or it will suffer yield depression. A North Carolina study showed that it wasn’t an ideal location for Lablab production. First, they couldn’t get good nodulation, which contributed to poor performance; this stresses the importance of inoculation. Next, the weedy control outperformed the Lablab, and indeed the weeds within the Lablab plot attained more than half of the biomass of the Lablab itself, thus stressing the necessity of early season weeding. Finally, North Carolina may just not get enough heat or UV intensity for the Lablab to thrive. Mucuna was also included in this study, and performed as poorly as Lablab.

Phaseolus coccineus (Scarlet runner beans) Scarlet runner beans are closely related to common beans, Phaseolus vulgaris. They are similar in some aspects but differ mainly in two areas. The first is size: scarlet runner beans are HUGE! The vegetative growth is larger, more vigorous, and robust, and so are the seeds and flowers. The other difference is that the scarlet runners have a perennial starchy root. Some indigenous groups in Mexico and Guatemala eat these roots, as well as the more commonly consumed beans and young pods. However, some report that the tuber is poisonous and should not be eaten. It’s likely that there are landraces that have been selected for edible tubers, or that the indigenous people employ various techniques to remove the toxins. They use the same inoculant as common beans, unlike most of the others in this publication, which use cowpea inoculant. Phaseolus species were developed in the Americas and were integral in the lives of many native peoples. Scarlet runners’

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Lablab at full canopy closure. The holes in the leaves are caused by leaf cutting bees.

The bright flowers attract beneficial insects, the beans are edible, and the roots fix nitrogen.

life cycle exactly matches that of corn; this was done by design. Their growth habit is suitable and their harvest time is right to be intercropped with corn. This is done throughout parts of Central and South America at altitudes above 1,500 feet. Scarlet runners need a bit more support than common beans, so when scarlet runners are used with corn, the planting density of the beans is reduced to a ratio of 1 bean to 10 corn instead of 1 to 1 as with common beans. Not all tall-growing plants may be used as companions with scarlet runner beans, as Hamburdă et al. (2014) found that there was a degree of yield lag (-70 percent from mean) when planted with Jerusalem artichokes, but when planted with sunflowers, scarlet runners performed 20 percent higher than the mean in Romania. In another experiment, scarlet runner grown with corn in Wisconsin significantly improved dry-matter yield, almost doubling it over mono-cropped corn. The Romanian group concluded that runner beans were economical to intercrop with both corn and sunflowers and that the beans created an ideal microclimate for their intercrop. Because scarlet runners are more adapted to higher elevations in the

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Continued from Page 36 tropics (much like coffee), it’s important to look for locally adapted varieties. In Central America and Mexico, there are landraces of scarlet runner that have been selected for many situations, including hot and dry climate areas. Some varieties are day-length dependent and may not set fruit the first year. So, if no varieties are specifically adapted to your area and you decide to create your own selection, patience is key. Usually when beans are planted, the cotyledons rise out of the soil and open to catch light. Scarlet runner beans don’t do this at all. Their cotyledons stay beneath the soil surface, protected from harm. Another difference between scarlet runners and other beans is that they twine clockwise around poles, trellises, or other supports.

Scarlet runners are a bit of an anomaly with regard to the rest of the cover crops in this article. The others are tried and true cover crops according to research, but scarlet runners have the potential to be cover crops according to indigenous use. For a complete list of references please see the ATTRA publication: Cover Crop Options for Hot and Humid Areas. https://attra.ncat.org/attra-pubsummaries/?pub=570 Justin Duncan is a Sustainable Agriculture Specialist with the National Center for Appropriate Technology's Southwest Regional Office. He has a B.S. in agronomy from Prairie View A&M University and an M.S. in plant breeding from Texas A&M University. He’s spent years figuring out the nutsand-bolts of successful organic farming

in the humid South, concentrating mainly on sweet potatoes, strawberries, niche market ethnic specialty crops, cover crops, and drought mitigation techniques. He is currently working on cover crop research projects in south Texas to help farmers there build organic matter in their soil with funding from NRCS’s Conservation Innovation Grant. THE NCAT MISSION: Helping people by championing small-scale, local and sustainable solutions that reduce poverty, promote healthy communities, and protect natural resources.

Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com

Table 2. Source: This table was compiled by NCAT from a number of sources, including USDA-NRCS Plant Guides (www.nrcs.usda.gov/wps/portal/nrcs/detail/ plantmaterials/technical/publications/?cid=stelprdb1077238#Cover%20Crop%20Plant%20Guides), Food and Agriculture Organization of the United Nations Grasslands Species Profiles (fao.org/ag/agp/AGPC/doc/gbase/Default.htm), and College of Tropical Agriculture and Human Resources, University of Hawai’I at Manoa (https://www.ctahr.hawaii.edu/site).

Some agronomic characteristics of selected cover crops suitable forareas. hot and humid areas. Some agronomic characteristics of selected cover crops suitable for hot and humid species

zone soil pH

ARACHIS glabrata

7-11

soil type

seeding nitrogen rate lb/ fixed lb acre per acre

DM tons per acre

provides weed provides erosion soil secondary grazing? hay? reduction suppression compaction product?

seed size

salinity

beneficials

expected mycorrhiza germination rate%

germination time days

innoculant

water use stage

sandy 4.5-8.0 loam transplant

100

2.85

high

low

yes

“yes, ornamental”

yes

relieves

0.1 cm

pollinators

positive

transplant

N/A

cowpea group

establishment: high

5.0-7.0

any

2.2

high

low

yes

“yes, food”

light

relieves

0.6 cm

parasitoids

positive

14-21

cowpea group

mature: medium

CASSIA spp

3-11

5.0-7.5

any

100

1.87

high

“yes, medicinal”

no evidence

0.3 cm

pollinators

positive

cowpea group

mature: medium

CENTROSEMA molle/ pubescens

7-9

sandy 4.9-5.5 loam

250

1.64

medium

high

yes

“yes, medicinal”

yes

relieves

0.5 cm

pollinators

positive

cowpea group

intermediate: medium

CLITORIA ternatea

7-10

6.6-7.5

any

281

3.07

low

yes

“yes, medicinal, ornamental”

yes

relieves

0.6 cm

pollinators

positive

14-21

soy or cowpea

mature: medium

sandy loam

278

2.5

medium

high

“yes, fiber reduces, nematodes”

relieves

0.6 cm

habitat

positive

4-10

cowpea group

early: high

CAJANUS cajan

CROTALARIA juncea

9b-11b 5.0-7.5

DESMODIUM uncinatum

5.5-7.0

any

2.08

high

yes

“yes, medicinal”

light

relieves

0.3 cm

pollinators

positive

4-10

cowpea group

mature: medium

LABLAB purpureus

8-11

4.5-6.5

any

220

8.9

high

yes

“yes, food, ornamental”

yes

relieves

1 cm

pollinators

positive

7-14

bradyrhizobium

early: high

MUCUNA pruriens

9b-11 5.5-6.5 sandy

150

4.9

high

yes

“yes, medicinal”

yes

relieves

1.5 cm

nematodes

positive

3-14

cowpea group

early: high

PHASEOLUS coccineus

7-11

6.6-7.5

150

125

6.99

high

low

“yes, food, ornamental”

yes

relieves

2 cm

pollinators

positive

bean group

intermediate: medium

sandy 4.0-8.3 loam

100

15.61

medium

high

yes

relieves

0.2 cm

repels termites

positive

2-5

cowpea group

intermediate: medium

sandy loam

1.65

high

low

yes

“yes, food”

yes

relieves

0.3 mm

parasitoids

positive

5-7

cowpea group

early: high

STYLOSANTHES 8-11 guayanesis VIGNA radiata

7-11

6.2-7.2

any

Disclaimer: this information is based on what research was available at the time. Every field and farm is different so results will vary and will need to be tailored to your unique situation. Salinity: MT = moderately tolerant; MS = Moderately Susceptible; S = Susceptible Disclaimer: this information is based on what research was available at the time. Every field and farm is different so results will vary Seed weights vary by supplier.

Salinity: MT = moderately tolerant; MS = Moderately Susceptible; S = Susceptible Seed weights vary by supplier.

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Wheat trial. Photo courtesy of Mark Lundy, UCCE.

Low-input Wheat Trials Work to Improve Understanding of Heritage Grains

By: Konrad Mathesius | Agronomy Advisor University of California Cooperative Extension (UCCE) Sacramento, Solano, and Yolo counties Contributors: Mark Lundy | UC Cooperative Extension Specialist and Allison Krill-Brown | UC Davis

ike most farmers, Sacramento Valley farmers are often concerned with price fluctuations in commodity crops. With the increasing popularity of artisan bakeries in California,1 growers might be able to access new markets where bakers/millers might be willing to pay a premium for quality and variety, and where prices are not as intimately linked to the fluctuations of commodity markets. In order to better understand the potential and limitations of heritage grains (heirloom, or, simply, older varieties) researchers from the University of California (Allison Krill-Brown (UC Davis), Mark Lundy (UC Statewide Small Grains Specialist), Konrad Mathesius (UCANR) are working with local growers and bakers in the Sacramento Valley to quantify performance of those varieties relative to modern types. Data from these trials will ultimately help growers and bakers better understand the performance expectations of these varieties and thereby

agree on reasonable and sustainable prices for grain.

Challenges of Older Varieties

management aside, taller varieties can also lodge more easily in high winds simply due to their larger surface area.

A necessary part of management is knowing what the risks are. These trials will help quantify some of the difficulties typically associated with growing older varieties of wheat: higher lodging rates, lower yields, and greater susceptibility to disease.

Disease rates tend to be higher in older varieties because of the biological arms race between pathogens like stripe rust and host plants. Breeders select and propagate resistant genotypes in an iterative, yearly process. Thus, it’s not surprising that older varieties are more susceptible to disease than their modern counterparts, because, although diseases

Older varieties of wheat that do not include semi-dwarf genes that reduce plant height are more susceptible to lodging (falling over). Taller stalks are less capable of carrying a heavy spike, where the grain is located on wheat. This means that for the taller, heritage varieties, soil nitrogen availability needs to be relatively low compared to shorter, modern varieties to avoid a heavy head of grain that would make the plant more susceptible to lodging. Nitrogen

Preliminary data from the three locations in the first year’s (2017-18) trials show that varieties labeled as ‘heritage’ produced 48 percent the yield of the higher yielding modern varieties. All of the heritage varieties were significantly lower than the average, and none of the heritage varieties out-

have continued to evolve, selection on heritage varieties has not been actively occurring to respond to these evolving pathogens.

¹Compound annual growth rate (CAGR) for artisan baked goods was predicted to be 3.85% from 2018-2023, 2.5% CAGR is typically considered a strong indicator for growth and investment.

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yielded more modern counterparts. Lodging was an issue with the heritage varieties in two of the three trials. This was in spite of production practices that limited the amount of soil nitrogen available to the crop and the use of a lower planting density than would be typical for modern varieties.

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Advantages of Heritage Grains Despite some of the difficulties associated with growing them, heritage grains do offer some advantages. Given the fact that heritage grains should demand a higher premium, growers might be in a better position to take on the risks associated with growing them organically. Slow-release fertilizer inputs such as compost or other forms of organic material may be less of a risk for growers as heritage grains demand less nitrogen per acre because of their lower yield potential. Some studies around the world suggest that taller varieties of wheat (as heritage varieties typically are) can be favorable in out-competing certain types of weeds, but further studies would be needed in California and the west to determine whether the same results would occur given differences in cultural practices, water availability, and weed species. The question then arises for the consumer and the baker: do different varieties of wheat bring something to the table in terms of taste, baking performance, or flavor? Lab data from stone-ground samples of wheat grown at one of the trials in the 2017-2018 season show that modern varieties also perform better than their heritage counterparts in some traditional quality metrics: mixograph data shows that heritage varieties tend to gain and lose gluten strength more quickly during kneading and/or fermentation. From the same dataset, falling number (a measure of enzymatic activity that breaks down gluten and therefore affects dough shape) appears to be insignificant between heritage and modern varieties. Other factors, such as protein, were higher in the lowest-yielding heritage varieties (Red Fife, Øland), but were insignificant among other modern and heritage varieties. No significant difference in protein was found between any heritage or modern varieties when all three sites were analyzed together.

Continued on Page 42

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Why the Demand for Heritage Grains

negotiate better price points that incorporate risk and lower yield. Aside from quantifying important factors like price points, yield, and baking One caveat to any of this is that performance, this study should also generalization of varieties is limited help raise some level of curiosity among when environment is thrown into the consumers about the plasticity of mix. Annual changes in weather have wheat quality from a genetic but also shown to impact quality parameters in wheat more significantly from one year environmental standpoint. If nothing else, bakers will likely end up making to the next than varietal differences. a few more loaves of bread during the In other words, baking performance is not only a function of wheat variety but learning process, and that is something also of where it was grown, and whether that most people can get excited about. or not that year was a ‘good year’ in varieties to achieve an appropriate mixture of performance and flavor.

With agronomic disadvantages and relatively few advantages in baking quality, why would there be a demand for heritage or alternative grains? Some bakers have suggested that there are differences in flavor or texture between varieties, and some studies have confirmed differences in polyphenol levels using gas chromatography. An Italian study indicated that consumers did prefer heritage varieties over modern varieties Madeline standing in semi-dwarf wheat (Patwin 515 variety). in taste tests, but which Photo courtesy of Konrad Mathesius. heritage variety they preferred changed from one panel to another (i.e. the significant favorite among one panel became an insignificant non-favorite in another panel). Other panels showed no significant difference in preference among any particular variety. In order to quantify differences in flavor, texture, or performance, several California bakers will be given samples of different varieties of grain harvested in 2018. This will allow bakers to compare flours in their operation to at least determine if there is a detectable, subjective difference driven by variety. Initial lab work carried out earlier this year by the California Wheat Commission indicates that there are differences both in their numerical lab values but also subjectively in how dough might feel or ‘set-up’ during autolysis or steps prior to fermentation. With some of that information in hand, artisan bakers might be able to mix and match flour

References:

Lemerle, D., Verbeek, B. and Orchard, B. (2001), Ranking the ability of wheat varieties to compete with Lolium rigidum. Weed Research, 41, 197-209. doi:10.1046/j.13653180.2001.00232.x Appleby, A. P., P.D. Olson, and D.R. Colbert. (1976). Winter Wheat Yield Reduction from Interference by Italian Ryegrass. Agronomy Journal, 68(May-June), 463-466. doi:10.2134/agronj1976.0 0021962006800030007x Migliorini, P., Sandra Spagnolo, Luisa Torri, Marco Arnoulet, Giulio Lazzerini, Salvatore Ceccarelli.

the area in which it was grown. Any future agronomic and yield quality data from these trials will be available in the small grains section of the University of California (UC) Agronomy Research and Information Center: http:// smallgrains.ucanr.edu/Variety_Results/ Organic_Low_Input_2018_Variety_ Results/ Ultimately low-input, heritage wheat variety trials should help growers

(2016). Agronomic and Quality Characteristics of Old, Moderns, and Mixture Wheat Varieties and Landraces for Organic Bread Chain in Diverse Environments of Northern Italy. European Journal of Agronomy, 79, 131-141. doi:https://doi.org/10.1016/j. eja.2016.05.011 Comments about this article? We want to hear from you. Feel free to email us at article@jcsmarketinginc.com

Seven varieties of bread made from stone-ground wheat flour and grown at one site in Woodland, California. Three varieties of older semi-dwarf wheat (Alturas, Yecoro Rojo, Edison) and four varieties of heritage/ landrace wheat (Red Fife, Sonora, Chiddam Blanc de Mars, Øland). Photo courtesy of Teng Vang, California Wheat Commission.

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