Southeast Report

Cotton Foliar Diseases In The Southeast

How To Identify And Manage Target Spot And Areolate Mildew

BY MONTY BAIN

DADEVILLE, ALABAMA

For more information on Cotton Incorporated’s research on disease diagnosis and management, visit cottoncultivated. cottoninc.com. The diagnosis and management of foliar diseases in cotton is an area of focus for Cotton Incorporated’s Agricultural and Environmental Research team.

In the Southeastern states of the Cotton Belt, target spot and areolate mildew rise to the top of the list of troublesome cotton foliar diseases. Knowing that these two diseases pose a high risk of negative effects later in cotton’s growing season, Cotton Incorporated has teamed up with the University of Georgia to fund research on how to identify and manage these issues.

Identifying Foliar Disease

Target spot can be easily recognized by the appearance of rings on the leaf, hence the name “target spot.” Characteristic symptoms of target spot include brown lesions, sometimes approaching 2 cm (~1 inch) in diameter, exhibiting a series of concentric rings.

Usually, this disease develops on the lower leaves of the plant and does more damage as it moves upwards, causing potential yield loss. When this happens, it causes premature defoliation of the leaves that would normally contribute to boll development.

Areolate mildew causes small lesions to appear on leaves in the lower canopy. The lesions, 3-4 mm (~0.15 in) wide and restricted by a major leaf vein, are slightly chlorotic on the upper leaf surface with a white mildew growth on the lower surface.

Lesions may become necrotic and resemble bacterial blight. In severe cases, premature defoliation will occur. The most telling sign is the white powdery mildew growth on the underside of the leaf.

Disease Management

According to Bob Kemerait, the University of Georgia’s resident plant pathologist, both diseases can be controlled using fungicides, if farmers can find them.

“Abundant rain, high humidity and rank growth all contribute to problems with target spot and areolate mildew. It will be most important to stay on top of applying a fungicide between the first and sixth week of bloom if the conditions are wet and humid,” Kemerait said.

“If the crop is dry and suffering from drought, then a fungicide may not be needed. Scouting the crop is going to be very important this season because of the rising cost of inputs and the lack of availability for certain fungicides.”

Areolate mildew is more easily controlled by fungicides than target spot, but both need to be sprayed at the first sign of disease to stay ahead of it and gain significant control.

Kaitlyn Bissonnette, director of agricultural research for plant pathology and nematology at Cotton Incorporated says, “Understanding and developing tools to manage emerging disease threats is of paramount importance to keep cotton production profitable.”

Typical symptomatic lesion of target spot. Symptoms of areolate mildew. Note brown necrotic lesions and powdery white sporulation on underside of leaf in Appling County, Georgia.

Monty Bain is the Cotton Board’s regional communication manager for the Southeast. Email him at mbain@cottonboard.org.

Sprayer Nozzle Selection

This Small Part Plays A Big Role In Making A Crop

BY AMANDA HUBER

SOUTHEAST EDITOR

Nozzles are one of the least expensive parts on a sprayer that has the most effect. The correct nozzle recommendation, along with pressure, volume and other parameters for effective application can be found on the pesticide label, said Simerjeet Virk, University of Georgia Extension precision ag specialist. Producers should always start pesticide application by reading the label.

“If you have a worn nozzle or the wrong size or type, the chances of something going wrong are significantly increased,” Virk said.

A Complex Decision

Several factors can influence the coverage and efficacy required during spray applications for effective weed or pest control.

“Those factors include pressure, volume, boom height, droplet size, tractor speed and field conditions,” he said. “All play a part in good coverage of the crop.”

Nozzle type affects sprayer output, uniformity, coverage and drift. Consult the manufacturer’s catalog to select the nozzle that provides the desired output (flow rate and droplet size) specific to the application.

“Nozzle selection will also depend on the ground speed and pressure required to achieve the rate in gallons per acre,” Virk said.

What About Rotational Crops?

University of Georgia Extension weed specialist Eric Prostko says most cotton growers in Georgia readily adopted the Xtendflex (dicamba) or Enlist (2,4-D choline) crop production systems, which require the use of nozzles designed to mitigate potential off-target movement of the herbicides. But would these nozzles, engineered to deliver very coarse to ultra-coarse droplets, work for rotational crops?

“Since most cotton growers in Georgia also produce peanut, growers would like to be able to use these auxin nozzles for pest management in peanut thereby reducing the need for sprayers to be equipped with multiple nozzles,” Prostko said.

To compare the performance of standard flat-fan nozzles to auxin nozzles, Prostko coordinated seven on-farm research trials in commercial peanut fields over a three-year period. All agri-chemicals were applied by the grower and according to the grower’s typical production practices.

Prostko found that cotton producers could use the auxin nozzles for pest management in peanuts without concern for reduced pesticide performance.

“Consequently, growers can save approximately $200 to $500 per applicator/sprayer in extra nozzle expenditures depending upon nozzle type/spacing/spray boom width,” he said. Various research trials using the auxin nozzles in the two crops continues.

Another Time-Saving Option

Even if auxin nozzles could be used for both cotton and peanuts, there are other sprayer applications with a proper nozzle selection.

“Is there one nozzle that can do the best job across all pesticide applications? Probably not.” Virk said.

In this instance, he recommends using a multi-nozzle turret body.

“You can put three, four or five nozzles, depending on the type of turret body, which will work best for each type of application — herbicide, fungicide or insecticide — as you go through the season. You don’t have to take it on and off. All you do is change the turret to the type of nozzle you need.”

Time spent on sprayer maintenance, nozzle selection, set up and calibration will go a long way to helping ensure effective spray coverage and pest protection.

UGA Extension weed specialist Eric Prostko has conducted on-farm research trials to see if auxin nozzles could be used effectively in rotational crops, particularly peanuts for Georgia producers.

Midseason Irrigation Pointers

Avoid Water Deficit Stress At Critical Cotton Growth Stages

BY CARROLL SMITH

EDITOR

The initial bloom that appears near the bottom of the cotton plant is white. After pollination, it quickly turns pink and then red. July is typically the month that a field of healthy cotton puts on this colorful display across many rural landscapes.

Once a cotton plant reaches the bloom stage of development, it’s important to manage its nutrient and water needs to produce the coveted bolls in anticipation of an abundant harvest.

Peak Water Requirement

“If you look at a crop water-use curve for cotton, our peak water requirement is from about the third or fourth week of bloom up to the sixth or seventh week of bloom,” said Wes Porter, University of Georgia precision ag and irrigation specialist. “That’s where we absolutely can’t fall behind. If we cut water during that time, we will significantly reduce our yields.

“Three to six weeks into bloom, we already have a high boll load lower in the plant. However, the plant is still trying to bloom and form bolls higher on the plant while continuing to develop the bolls on the lower part of the plant.

“You need to water at this high stress time to ensure it can do both. My recommendation as we get further into the season is to apply ½-inch today, skip a day, then apply ½-inch the day after — kind of spoon feed the crop. This keeps the soil wet, and you don’t lose moisture. Very large or small irrigation events are not recommended as water can be lost or have little to no effect.”

Although there is always the potential exception to the rule, July is a hot, dry month.

“We typically have temperatures in the 90s every day with no reprieve,” Porter said. “Sometimes this will bring thunderstorms across the South. But we may go a week or two without any rainfall, especially if we don’t get any moisture moving up from the Gulf.

“During that time, it’s easy to fall behind on irrigation because we have so much going on. A lot of people get comfortable irrigating once a week or 1.5 times on average per week during that first 40 to 60 days after planting. But it’s important to make sure we are prepared, watch where our moisture levels

What If You Fall Behind?

Moving into July when cotton hits peak bloom, the above ground biomass is about equivalent to the below ground biomass, Porter said. The root system is extracting water a lot deeper than it was earlier in the season.

“If we have not paid close attention, we are now falling behind because we are using deep moisture and drying out the entire profile,” he said. “When you deplete the deeper soil moisture, you won’t catch up with overhead, sprinkler-style irrigation alone. That’s a scary place to be midseason.”

If a farmer gets to that point, Porter recommends backing off the irrigation rate and making multiple applications, if possible. This “bounce back” option — that includes two lower-rate applications fast enough to stay on top of water requirements — is possible with smaller overhead irrigation systems.

But with a larger overhead system that takes more than 24 to 36 hours to make an application, survival mode becomes a reality. To maintain the water requirement, the system then has to run almost continuously.

Advanced Irrigation Scheduling

Another consideration, according to the UGA Cotton Team Newsletter, “If proper growth regulator is applied, it will prevent vegetative growth as it should. If rain chances are low, irrigation will be required to get the fertilizer to the plant by irrigating it in and allowing the plant to uptake the nutrients.”

However, Porter said, it’s also important not to overwater the crop, which could affect yield. To avoid this scenario, he strongly encourages anyone who is irrigating cotton to use an advanced irrigation scheduling method whether it’s a wet or a dry year.

“Use some type of computer model, soil moisture sensor or the basic checkbook irrigation method,” he said. “Most universities publish a checkbook method for their region. It shows the weekly water requirement for the crop.

“You should keep up with rainfall and supplement the difference. With our sandy soil types in Georgia, two to three days is about all the water we can store.”

Another irrigation scheduling tool is the SmartIrrigation Cotton App. According to UGA AgWET, “The Cotton App uses an evapotranspiration-based model to estimate when irrigation is necessary and provides the user with an estimate of how much water should be applied. It does not require any sensors, sends the user notifications when action is needed and is currently available at no cost.”

If a farmer chooses to use a soil moisture sensing system, it directly measures soil moisture in the field. Some of the irrigation manufacturers have programs as well. Lindsay offers FieldNET Advisor that can be used without sensors. Valley offers Valley Scheduling advanced management software. Reinke has partnered with Crop Metrics to offer the CropX sensors system through most of their dealers.

“Valley Scheduling and the CropX systems do require sensors, but they can be set up specifically to cotton,” Porter said. “And there are a lot of sensor companies that offer aftermarket sensor options you can purchase to put in your fields and utilize, too.”

Weighting Sensor Depths

When using a soil moisture sensing system, Porter said it is a good idea to weight the sensor depths according to the root depth by assigning percentage values to the shallow sensors and deeper sensors.

For example, early in the season, 70% to 80% of irrigation decisions potentially would be based on the shallow sensor. As the cotton grows, the percentage value on the shallow sensor might drop to 50% combined with a 25%/25% split on two deeper sensors.

Using a weighted average that matches root growth instead of using a simple average is typically more accurate when trying to make cotton irrigation decisions based on soil moisture sensor graphs.

“You have to consider where we are actually extracting water from and where the plant needs water replenished,” Porter said. “That’s how I assign a percentage value for the different sensors — that extend to different depths — to match root growth at the time.

“If the roots are extracting water from deeper in the ground at a certain point, make sure that factor is part of your irrigation scheduling decision when using soil moisture sensors. It’s important to make these adjustments throughout the growing season.”

For questions about cotton irrigation scheduling in your specific area, reach out to your local Extension agent.

Figure 2: 40 kPa (or near optimal) trigger level, May 22-June 21, 2022.

Figure 3: 70 kPa (or dry) trigger level, May 22-June 21, 2022.

Trigger Levels

As shown in Figures 1, 2 and 3, if a wet or optimal soil moisture is managed throughout the season, the deeper soil moisture is maintained at a lower or more wet level and is easier to recover with irrigation and rainfall events. However, as can be seen in Figure 3, the crop has remained in stress during the time frame shown, and all depths have utilized significant moisture.

In these three cases, the treatment represented by Figure 1 will most likely either cause a yield reduction or profit reduction due to over irrigation. Figure 2 is an optimal treatment for cotton, and 3 is much too dry, causing a reduction in yield.

It should be noted that the soil type for these sensors is a loamy sand soil. These trigger levels are not relavant in all soil types. You should consult recommendations for soil types specific to your region. — Wes Porter

July In The Texas Southern High Plains — Not A Time To Underthink A Nematode

Sample Now For Next Season’s Plan

BY BRENDA CAROL

By this point in the season, growers are thinking about all sorts of issues with their cotton crop. Nematodes are probably not topof-mind unless something is going on in the field that doesn’t quite make sense.

If that’s the case, it’s time to sample if nematodes are a suspected culprit.

“Sampling is most important when you are concerned that a new field may have a problem, or if you are growing a nematode-resistant variety and are concerned that there may still be a nematode problem,” said Terry Wheeler, Ph.D, plant pathologist/nematologist, Texas A&M AgriLife at Lubbock, Texas.

“Later season sampling may also have some value if you are growing another crop and want to check on nematode buildup that may affect the next year’s cotton crop.”

Although there is not much that can be done to remedy the issue in the present, next year is an entirely different story. With an ever-increasing arsenal of nematode-resistant varieties, chemical control options and field management, the opportunities to gain an upper hand on a nematode issue are better now than they’ve ever been.

Rise Of Reniform

Beyond generally suspecting a nematode issue in a field, it’s important to identify exactly what species of nematode is present. The two most likely culprits are root-knot and reniform. This knowledge will impact future management decisions particularly as it relates to variety selection, according to Wheeler.

“In this part of Texas, the reniform nematode is slowly increasing across acreage,” she said. “In other parts of Texas, the reniform nematode is showing up in new fields or areas. Root-knot nematode has been stable in its distribution for decades.”

Root-knot nematode covers the most acres in cotton (and peanuts in other parts of Texas) and can cause a low to moderate amount of damage, according to Wheeler.

“Reniform nematode is much more limited in its distribution but can cause 50% to 70% yield loss once it is well distributed in a field,” she said. “This can be problematic, especially if the producer is not doing anything to manage it.”

Variety Selection

Battling nematodes often starts with a bag of seed. Today, there are numerous cotton varieties with varying degrees of root-knot and/or reniform resistance.

“With root-knot nematode, there are partially or highly resistant varieties with Deltapine, FiberMax, Stoneville and PhytoGen,” Wheeler said. “Dyna-Gro also has some, but I have not been able to test any to see how well they perform. With reniform nematode, the big news is that there are now several reniform/rootknot nematode resistant varieties that combine resistance to both.”

Those varieties include, but are not necessarily limited to, the following, according to Wheeler:

• PHY 205 W3FE • PHY 332 W3FE • PHY 411 W3FE • PHY 443 W3FE • DP 2141NR B3XF • DP 2143NR B3XF

“With reniform nematode, I would expect the resistant varieties to increase cotton yields relative to all the reniform nematode susceptible varieties; plus, the reniform-resistant varieties will lower the nematode population around 60%,” she said.

“Typically, the highest yielding resistant variety in my trials doubles the yield compared with reniform susceptible varieties.”

Rotation

As always, rotation is a key management option when it comes to nematode issues.

“The only other alternative that I recommend with reniform nematode is to rotate one to two years out of cotton with a non-host like sorghum or corn following each cotton crop,” Wheeler said. “The situation regarding reniform nematode resistance is all upside at this point.

“For root-knot nematode, depending on the resistant variety, there may be no increase in yield compared with a root-knot susceptible variety. The best root-knot nematode resistant varieties, in terms of yields, average about 17% higher than susceptible cotton varieties, and that typically is found in some of the PhytoGen varieties or ST 4946GLB2.”

Nematicides In The Mix

As growers consider their options in 2023, supplemental chemical control is always a tried-and-true input in challenging nematode situations and is equally effective on root-knot and reniform.

The recommended at-plant options, according to Wheeler, include Velum and AgLogic. Post-plant options include Vydate CLV or Return XL.

Where To Send Nematode Samples

The cost for running nematode samples across the country generally ranges from free to $35-$50 per sample. ■ The diagnostic clinic at Texas A&M in College Station will run nematode samples. Start by accessing the Plant Nematode Detection Form at http://plant clinic.tamu.edu. The form contains nematode sampling guidelines and nematode sample shipping instructions. The address is Texas Plant Disease Diagnostic Laboratory, 1500 Research Parkway, Suite A130, Texas A&M University Research Park, College Station, TX 77845. ■ A&L Plains Analytical Laboratories also runs nematode samples. The address is 302 34th St., Lubbock, TX 79404. For more information and specific instructions, email the lab at alplainslab@gmail.com.

Brenda Carol is a freelance writer based in San Luis Obispo, California. E-mail her at brenda@carolcommunications.com.

CCOY

The Cotton Consultant of the Year (CCOY) Award marks more than four decades. The award recognizes a consultant who has made great contributions to the cotton industry through outstanding customer relations, leadership and innovation. It honors a consultant who not only meets these requirements but also exceeds them.

Syngenta and Cotton Farming magazine — CCOY sponsors — are soliciting your help in selecting the 2022 recipient, who will be named at a special celebration Friday, Feb. 24, 2023, at the Peabody Hotel in Memphis, Tennessee.

The winning consultant and the person who nominates the winner receive a two-night hotel stay and airfare to Memphis. The 2022 CCOY recipient also will be featured in a four-page salute in the February 2023 issue of Cotton Farming.

Submit nominations by July 31, 2022.

Mail: Carroll Smith 7201 Eastern Ave. Germantown, TN 38138 Scan/Email: csmith@onegrower.com

You can print an electronic version of the form located on the Cotton Farming website at www.cottonfarming.com.

Nominate online: cottonfarming.com/ccoy

Cotton Consultant of theYear2022

NOMINATION FORM

If you would like to nominate a consultant deserving of this outstanding recognition, please take a moment to fill out the following form.

Please use a separate page for biographical/professional information. Additional recommendations via letters or emails from other farmers, consultants and industry members are also encouraged to provide support for the nominee.

Consultant’s Name: Company Name: Mailing Address: City: Phone: State: Email: ZIP:

In your own words, please tell us why you are nominating the consultant above for the Cotton Consultant of the Year Award. Additional pages may be attached, emailed or attached to the online nomination form. Background:

Biographical/Industry Involvement Background. This information as well as support letters may be attached to this form, emailed or attached to the online nomination form.

Your Name: Mailing Address: City: Phone: State: Email: ZIP:

Todd Westerfeld

@westy1241

Todd Westerfeld, a Central Texas farmer in Moody, Texas, has gained a substantial following on social media over the past several years. Using Instagram as his main platform, he shares everything from the daily ins-and-outs of farming in the Texas heat to insightful thoughts on life as a farmer in general.

Instagram: The Good And The Bad

Being a photo-centric person, Westerfeld prefers Instagram as his main platform. “I’ve always been a big photography person,” he said.

He discussed the transition over the years from strictly posting pictures to now incorporating more stories for people to see as well.

“It’s a good way to chronicle what you’re doing, and it’s also a good way to communicate with people and see what’s going on across the nation. The networking aspect has been quite amazing; not only for me to give information to people, but I’m also learning a lot.” Westerfeld emphasized the pros and cons of social media to be based on the person behind the screen. “People don’t want to see the bad; that’s not what gets the clicks,” Westerfeld said. “I try to paint the picture of ‘hey, it’s not perfect.’ Instead of focusing on their life first and letting social media tell the story, people are too concerned about what others think is going on in their life.”

He reiterated the importance of stepping away when necessary.

“The beauty of social media is you’re not forced to use it. If something’s bothering you, just step away from it. You don’t have to be on social media, and sometimes stepping away from it is one of the best things you can do to let your mind recharge,” he said.

Social Media And Policy

All that being said, Westerfeld still views social media as having good aspects as well.

He said they’ve implemented several things on their farm that came of his interactions on social media. High-speed planters, high-speed tillage and other technologies are among these new implementations.

“You get to talk to enough people now that you can learn more about things and debug to make things a little bit easier in making decisions.”

He sees more networking potential and would like to find ways to connect with others who can help make big decisions for the agricultural industry.

“A big thing I’m wanting to push for right now is for some type of federal or state help with designating farmland as farmland,” Westerfeld said. “With this solar farm boom we’ve been experiencing, wind farms and developments, there is a point in which we are going to exhaust our farmland. When that point is

“Influencers In Their Fields” spotlights those providing a voice for American agriculture through social media. If you know of an influencer you’d like to see featured, contact Cassidy Nemec at cnemec@ onegrower.com.

reached — and more importantly realized — it’s too late.”

He continued by explaining what could happen when it is too late.

“When you put in housing additions and solar farms, you can’t really just reclaim it back into farmland,” he warned.

Interacting Through His Platform

Westerfeld noted the lack of young farmers around his area of Central Texas and how social media keeps him close with like-minded individuals.

“Having that networking and being able to talk to people across the country, to laugh with people, to feel bad for people… it kind of brings that neighborhood mentality I wouldn’t necessarily have otherwise.”

Westerfeld said he finds it laughable that so many people see his content and have an interest in it.

“I don’t think what I’m doing — in my mind — is more than me just talking, but to so many people, I forget how nice it is for them to be able to learn. Whether it be people who’ve farmed their whole life and are now just getting to see the technology and equipment coming along, or even people who’ve never farmed in their life and are getting to learn what farming can actually be,” he said.

He further commented on how big for agriculture it could be if more people outside of the industry were to be exposed to this content and learn the crucial role farming plays in their lives.

“Being able to teach the general public that we’re not out there to kill them — and that what we’re actually doing is sustainable and safe — is good. Trying to get that pushed out to the general public, however, is a different story.”

In the end, Westerfeld hopes to make a positive impact on the agricultural industry and those who choose to interact with him on social media.

“Ultimately, if I can make people smile or give good information… those are the two things that I’m after.” “Being able to teach the general public that we’re not out there to kill them — and that what we’re actually doing is sustainable and safe — is good. Trying to get that pushed out to the general public, however, is a different story.”

CONSTRUCTION GUIDE

Mississippi State Extension put together a publication covering the Irrometer Watermark series. The assembly guide below depicts the Irrometer Watermark 200SS, a granular matrix sensor commonly used in Mississippi for scheduling irrigation. This publication provides a step-by-step guide to proper Watermark sensor construction. Following these steps will make the sensors easier to install at the intended depths and easier to remove at the end of the season.

TOOLS & SUPPLIES

The tools and supplies pictured below will be used. Fifteen feet of sensor wires is usually convenient.

One set of 6-inch, 12-inch, 24-inch, and 36-inch sensors will require one 10-foot stick of ½-inch Class 315 PVC pipe. Select the correct PVC specifications to avoid frustrations later.

ABS-PVC transition cement is best for joining the ABS sensor collar to a primed PVC section. Using a different cement can increase the risk of sensor-PVC separation during removal.

USE THIN WALL!

ASSEMBLY

STEP 1: Using the PVC cutter, cut a PVC length that is 10 inches longer than the intended sensor depth to simplify sensor removal. Following the color code below for that sensor depth, wrap a ring of colored electrical tape 4 inches from one end of the cut PVC section.

Sensor depth PVC length Tape color 6” 16” blue 12” 22” white 24” 34” red 36” 46” yellow

STEP 2: Using the electric drill and a 3⁄16-inch drill bit, make a weep hole ¼ inch from the untaped bottom end of the PVC section.

STEP 3: Apply PVC primer at least ½ inch inside the bottom end of the PVC section. Be ready for drips.

For more information, please contact Extension Irrigation Specialist Drew Gholson at drew.gholson@msstate.edu or (662) 390-8505.

STEP 4: After a few minutes of drying, thread the sensor wires from the bottom end of the PVC section to the top end until the sensor collar meets the bottom end. Bundle the extra wire.

STEP 5: Carefully apply an appropriate amount of ABSPVC transition cement to the sensor collar.

STEP 6: While aligning the sensor weep slot with the drilled weep hole, push the sensor collar fully into the bottom end of the PVC section. Ensure that the weep hole will allow water to drain out.

STEP 7: Wrap a ring of black electrical tape so that the distance between the bottom of the tape and the middle of the attached sensor equals the intended sensor depth. After installation, the bottom edge of the black electrical tape should be flush with the ground. Placing a rubber washer around the PVC section can reduce water flow down the installation hole.

STEP 8: Slide a rubber cap onto the top end of the PVC section. The construction is now complete!

This publication is a contribution of the National Center for Alluvial Aquifer Research (NCAAR), the Mississippi State University Extension Service, and the Row-Crop Irrigation Science Extension and Research (RISER) initiative. NCAAR is supported by the Agricultural Research Service, United States Department of Agriculture (USDA), under Cooperative Agreement number 58-6001-7-001. RISER is supported jointly by Mississippi Soybean Promotion Board, Mississippi Corn Promotion Board, Mississippi Rice Promotion Board, Cotton Incorporated, Mississippi Peanut Promotion Board, and by the Conservation Innovation Grants program at USDA’s Natural Resources Conservation Service under award number NR203A750008G007.

This information and photos were provided by the Mississippi State University Extension Service; Jacob Rix, Extension/Research Associate; Himmy Lo, PhD, Assistant Extension/ Research Professor; Drew Gholson, PhD, Assistant Professor; and Mark Henry, Extension Associate, Delta Research and Extension Center.