VOL. 21/NO. 1
Spring 2020
The Official Publication of The Tennessee Nursery and Landscape Association
Phytophthora Root and Crown Rot of Boxwood Plus, The Southern Root Knot Nematode
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VOL. 21/NO. 1 •
The Official Publication of The Tennessee Nursery and Landscape Association
COVER STORY Phytophthora Root and Crown Rot of Boxwood
8
INDUSTRY NEWS Jimmy Driver Honored as SNA Honorary Member
15
DEPARTMENTS From the President................................................................................................................... 6 TNLA Sponsors........................................................................................................................ 6 TNLA News........................................................................................................................... 14 Calendar of Events.................................................................................................................. 22 Welcome, New TNLA Members............................................................................................ 22 Index of Advertisers................................................................................................................ 22
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tennessee greentimes SPRING 2020
Spring 2020
FEATURE STORY The Southern Root Knot Nematode
16
The Tennessee Nursery and Landscape Association serves its members in the industry through education, promotion and representation. The statements and opinions expressed herein are those of the individual authors and do not necessarily represent the views of the association, its staff, or its board of directors, Tennessee GreenTimes, or its editors. Likewise, the appearance of advertisers, or their identification as Tennessee Nursery and Landscape Association members, does not constitute an endorsement of the products or services featured in this, past or subsequent issues of this quarterly publication. Copyright Š2020 by the Tennessee Nursery and Landscape Association. Tennessee GreenTimes is published quarterly. Subscriptions are complimentary to members of the Tennessee Nursery and Landscape Association Third-class postage is paid at Jefferson City, MO. Printed in the U.S.A. Reprints and Submissions: Tennessee GreenTimes allows reprinting of material. Permission requests should be directed to the Tennessee Nursery and Landscape Association. We are not responsible for unsolicited freelance manuscripts and photographs. Contact the managing editor for contribution information. Advertising: For display and classified advertising rates and insertions, please contact Leading Edge Communications, LLC, 206 Bridge Street, Franklin, TN 37064, (615) 790-3718, Fax (615) 794-4524.
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From the President Bert Driver
TALK ABOUT THE WEATHER ... yeah, yeah, yeah
TNLA Would like to
THANK
the following companies for being
Membership Sponsors GOLD MEMBERSHIP SPONSORS Barky Beaver Mulch & Soil Mix, Inc. Blankenship Farms and Nursery Botanico, Inc. Flower City Nurseries Living Earth Nashville Living Earth Knoxville Nashville Landscape Systems, Inc. Putnals Premium Pine Straw, Inc. Randall Walker Farms Safeguard Nursery Products Swafford Nursery, Inc. Tennessee 811 Tennessee Wholesale Nursery Warren County Nursery, Inc.
SILVER MEMBERSHIP SPONSORS
M
ost people in the green industry are driven to an outdoor lifestyle, which dictates that we follow multiple sources of weather updates on a daily basis — if not hourly! Day-to-day operations are controlled by the jet stream, topography, some say Short Mountain, and the Gulf of Mexico. These components combined help explain why it is was 70 degrees on Christmas Day and why on occasion we can just as easily drop below zero. Rain, wind, humidity, heat and cold obviously dictate the growing season and how plants perform, when we can plant, when we can harvest, and when we can get paid. It is also the reason plant life does so well here in Middle Tennessee. Blessed with a subtropical temperament climate most of the time, there are over 150 species of native trees on the Cumberland Plateau alone, which is more than the entire continent of Europe. Yes, the weather patterns affect job sites, harvest, sales and more importantly, our innate need to be connected to the Earth and why it is we are so drawn to this area. With the challenges that the weather creates, it also is the reason we have multiple creeks, rivers, and lakes. We are connected to the flow of life that happens here. We are in nature, and it is diverse, unpredictable, and the very thing we depend on to survive as a species. Hence, the weather is not just idle chit chat. Just ask a developer, a builder, a farmer, or a business owner. Everything we do and all of the commerce that we create is dictated by the weather, so it is important to remember just how critical it is to take care of what we have here in Tennessee. “We realize that the severe weather conditions during the past year has been very traumatic to our industry resulting in great losses of saleable plants and therefore our overall economy will be greatly affected. We must all come together and pool our thoughts and ideas in the best effective ways to prepare for another season. Any suggestions on how we can better serve you as an association are always appreciated and will be seriously considered. Our potential is limitless in this great and growing industry that we have chosen to be a part of, and may we keep this thought foremost in the coming year.” — Jimmy Driver, TNA President’s Message, 1985 Allow me to echo that sentiment: we have certainly all seen this industry ebb and flow, but overall, this is a uniquely positioned group that can work together to make it better than ever. One way to help yourself and the entire association is to fill out and respond to the upcoming survey: “2020 Tennessee Nursery Survey”. Why? So that going forward we can look at our elected officials in the eye and inform them how good this industry is and how much money this industry contributes to the economy. We need that data to have a seat at the table. Thus, I encourage you to respond to the survey, talk to your fellow nurserymen, and participate in an organization that has a long, distinguished heritage going back over 100 years. Respectfully,
Carpe Diem Farms Dayton Bag & Burlap Co. Old Courthouse Nursery Scenic Hills Nursery Turf Mountain Sod 6
tennessee greentimes SPRING 2020
Bert Driver President
The Tennessee Greentimes is the official publication of The Tennessee Nursery & Landscape Association, Inc. 115 Lyon Street McMinnville, Tennessee 37110 (931) 473-3951 Fax (931) 473-5883 www.tnla.com Email: mail@tnla.com Published by Leading Edge Communications, LLC 206 Bridge Street Franklin, Tennessee 37064 (615) 790-3718 Fax (615) 794-4524 Email: info@leadingedge communications.com
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Editors Dr. Bill Klingeman Dr. Amy Fulcher Associate Editors Dr. Nick Gawel Dr. Frank Hale Dr. John Sorochan TNLA Officers President Bert Driver Bert Driver Nursery
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1st Vice President Morgan Adcock Scenic Hills Nursery 2nd Vice President Michael Gallagher Heather Farms Nursery 3rd Vice President Terri Turner Turner & Son’s Nursery Secretary-Treasurer Cody Walker Walker Nursery Co. Associate Director Justin Woodlee Tennessee Valley Tractor & Equipment Ex-Officio Jon Flanders Botanico, Inc. Executive Director Louree Walker
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Cover Story
Phytophthora Root and Crown Rot of Boxwood By Dr. Fulya Baysal-Gurel, Assistant Professor of Plant Pathology
Tennessee State University Otis L. Floyd Nursery Research Center Ornamental Pathology Program McMinnville, TN 37110 fbaysalg@tnstate.edu
P
hytophthora root and crown rot of boxwood is caused by several species of Oomycetes (known as water molds). Some of the more frequently encountered Phytophthora species include P. nicotianae, P. cinnamomi, P. citrophthora and P. occultans. Many plant species, including American (common), Japanese, and English boxwood, are susceptible to this disease. The pathogen can infect all growth stages of field and container grown boxwood plants. Warm, humid and rainy conditions favor disease development. Phytophthora spp. can survive in soil or potting substrate as resting spores (oospores, chlamydospores), and inside infected plant tissues as mycelium for long periods. Meantime, these resting spores are available to infect other healthy boxwoods or other host plants. When the environmental conditions are favorable, chlamydospores and oospores produce new mycelium or sporangia. Sporangia release zoospores into soil, and the zoospores swim toward healthy roots through saturated soil or irrigation water. The general symptoms presented by infected plants include wilting, stunting, leaf shed, limb dieback, leaf chlorosis, off-color foliage, crown rot (gray to brown color) (Figures 1–4) and root rot (roots appear brown and water-soaked) (Figure 2). Depending on the disease progression in roots, foliar symptoms may be observed on a few branches or the entire plant (Figure 3).
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Figure 1. Left: Symptoms of boxwood Phytophthora crown rot. Right: Dark lesions beneath the bark may also be apparent outside infected stems (Right photo credit, Elizabeth Bush, Virginia Polytechnic Institute and State University, Bugwood.org)
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Figure 3. Foliar symptoms of boxwood Phytophthora root and crown rot.
Figure 2. Symptoms of boxwood Phytophthora root and crown rot; positive confirmed case using Phytophthora immunostrip test.
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Figure 4. A boxwood plant that was transplanted too deeply now exhibits Phytophthora root and crown rot symptoms.
Cover Story Continued
What makes Phytophthora root and crown rot so difficult to control?
Why is it important to rotate fungicides in programs that control plant diseases like Phytophthora root rot and crown rot?
Phytophthora root and crown rot is stimulated by rising soil temperature and moisture, poor drainage, excessive irrigation, extended periods of heavy rainfall, flooding or when plants are planted too deeply (Figure 4). Fungicides need to be applied before the establishment of the pathogen. Therefore, preventative fungicide/biofungicide applications in a rotation are critical to control Phytophthora root and crown rot. Once it establishes, management of Phytophthora will require an integrated approach. Effective control strategies focus on scouting and early diagnosis along with sound cultural practices such as sanitation, good drainage, proper irrigation, irrigation water treatments, crop rotation, biofumigation and chemical/biological control. Good cultural practices include sanitizing tools, equipment, and reused pots (or avoid reusing pots altogether). If the production area or field had Phytophthora issues in the past, boxwood and other susceptible host plants should not be planted at least for three years.
Pathogen resistance to fungicides has been documented and the performance of many fungicides has been affected, to some degree, by plant pathogens that have developed resistance. Therefore, it is important to develop a fungicide rotation program that uses different modes of action, as indicated by their respective Fungicide Resistance Action Committee (FRAC) codes, as an important tool in limiting risk of fungicide resistance development. In 2018, a trial was initiated by the Tennessee State University (TSU) Ornamental Pathology Program to evaluate fungicides alone, and in rotation, with treatments made on a 14-day schedule to control Phytophthora root rot. Boxwood ‘Green Velvet’ plants in 1 gal black plastic nursery containers were inoculated with P. nicotianae grown on rice grains. Inoculum consisted of four rice grains placed 5 cm below the potting substrate surface on the four opposite sides of the plant. Non-treated, non-inoculated
Table 1. Evaluation of fungicides alone and in rotation programs for the control of Phytophthora root rot of boxwood (Trial 1) Phytophthora root rot severity (%) y
Total fresh weight (oz)
Non-treated, non-inoculated control
0.0 d x
0.6 a
Non-treated, inoculated control
75.6 a
0.3 b
Treatment and rate (application dates) z
Empress Intrinsic 23.8SC 3 fl oz/100 gal (1,2)
Application method
FRAC code
Restricted-entry interval
Drench
11
12 hr
11.3 c
0.6 a
Spray
7 + 11
12 hr
23.1 b
0.6 a
Orvego SC 14 fl oz/100 gal (1,2)
Drench
45 + 40
12 hr
21.9 b
0.4 b
Empress Intrinsic 23.8SC 3 fl oz/100 gal (1); alt Orvego SC 14 fl oz/100 gal (2)
Drench; Drench
11; 45 + 40
12 hr; 12 hr
5.6 cd
0.6 a
Orvego SC 14 fl oz/100 gal (1); alt Orkestra Intrinsic SC 10 fl oz/100 gal (2)
Drench; Spray
45 + 40; 7 + 11
12 hr; 12 hr
5.0 cd
0.7 a
Segovis 1.67SC 3 fl oz/100 gal (1); alt Subdue Maxx 22ME 2 fl oz/100 gal (2)
Drench; Drench
U15; 4
4 hr; 0 hr
5.6 cd
0.6 a
≤ 0.0001
≤ 0.0001
Orkestra Intrinsic SC 10 fl oz/100 gal (1,2)
P – value
z Application dates: 1 = 2 Nov.; 2 = 16 Nov. y Disease severity was based on percentage of roots affected. x Values are the means of eight replicates; treatments followed by the same letter within a column are not significantly different at P ≤ 0.05. 10
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Cover Story Continued and inoculated containers served as controls. Orkestra Intrinsic (10 fl oz/100 gal) (a.i. fluxapyroxad + pyraclostrobin) was applied as a spray to run-off using a backpack CO2-pressurized sprayer at 40 psi, while Empress Intrinsic (3 fl oz/100 gal) (a.i. pyraclostrobin), Orvego (14 fl oz/100 gal) (a.i. ametoctradin + dimethomorph), Segovis (3 fl oz/100 gal) (a.i. oxathiapiprolin), or Subdue Maxx (2 fl oz/100 gal) (a.i. mefenoxam) were applied as a drench (4.1 fl oz/plant). Total fresh weight was recorded, and severity of Phytophthora root rot was assessed using a scale of 0–100% of roots that showed an affect at the end of the trial. All fungicide treatments significantly reduced Phytophthora root rot severity compared to non-treated, inoculated control boxwood plants (Table 1). All fungicide rotation programs, as well as Empress Intrinsic alone, most effectively reduced Phytophthora root rot disease severity. Plants treated with Orvego alone had lower fresh weight compared to all other treatments, and were no different than the non-treated, inoculated control. In another trial, the TSU Ornamental Pathology Program also evaluated fungicides alone and in rotation programs for controlling Phytophthora root rot on rooted cuttings of boxwood that had been inoculated with P. nicotianae grown on rice grains. Non-treated, non-inoculated and inoculated containers served as controls. Treatments were Subdue Maxx (2 fl oz/100 gal) (a.i. mefenoxam) only (drench) at a 10-wk interval and fungicide rotation program (Pageant Intrinsic 38WG (6 oz/100 gal) (a.i. boscalid + pyraclostrobin) (spray) alternated with Chipco 26019
(2 fl oz/100 gal) (a.i. iprodione) (spray) alternated with Empress Intrinsic (3 fl oz/100 gal) (a.i. pyraclostrobin) (drench). Total fresh weight and plant height were recorded, and severity of Phytophthora root rot was assessed using a scale of 0–100% roots affected. Phytophthora root rot disease pressure was high in this trial with non-treated, inoculated control rooted boxwood cuttings showing 53.0% disease severity. Both the fungicide rotation program (Pageant Intrinsic, Chipco 26019 and Empress Intrinsic) and Subdue Maxx alone significantly reduced Phytophthora root rot severity compared to the non-treated, inoculated control plants (Table 2). All fungicide-treated plants had increased plant height and total fresh weight compared to non-treated, inoculated control plants. Boxwood plants in the rotation program were taller than plants in both control groups.
Prompt action helps to manage Phytophthora root and crown rot For boxwood and other susceptible host plants, scouting and proper identification of the disease and the disease-causing agent are critical for implementing of effective disease control strategies. If you would like to confirm that Phytophthora root and crown rot has infected your boxwood plants, you can submit a sample to your local university’s plant diagnostic laboratory.
Table 2. Evaluation of fungicides alone and in rotation programs for the control of Phytophthora root rot of boxwood rooted cuttings (Trial 2) Treatment and rate (application dates) z
Application method
FRAC code
Restricted-entry Phytophthora root interval rot severity (%) y
Total fresh weight (oz)
Non-treated, non-inoculated control
0.0 b v
46.9 b
0.5 a
Non-treated, inoculated control
53.0 a
21.8 c
0.3 b
8.0 b
62.4 ab
0.6 a
1.2 b
70.3 a
0.6 a
≤ 0.0001
0.0006
0.0042
Subdue Maxx 22ME 2 fl oz/100 gal (1,5)
Drench
Pageant Instrinsic 6 oz/100 gal (1,2); alt Chipco 26019 2 fl oz/ 100 gal (3); alt Empress Intrinsic 23.8SC 3 fl oz/100 gal (4)
Spray; Spray; Drench
P – value
7 + 11; 2; 11
12 hr; 12 hr; 12 hr
z Application dates: 1 = 7 Nov.; 2 = 21 Nov., 3 = 12 Dec., 4 = 2 Jan., 5 = 9 Jan. y Disease severity was based on percentage of roots affected. x Percent plant height increase was calculated according to the formula: [(final plant height — initial plant height)/initial plant height x100]. v Values are the means of five replicates; treatments followed by the same letter within a column are not significantly different at P ≤ 0.05 12
Plant height increase (%) x
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TNLA News
How Do You Benefit from Completing the Tennessee Nursery Survey?
T
NLA and MTNA are working with the University of Tennessee to conduct a comprehensive economic analysis of the Tennessee Nursery Industry. By completing your survey, you help document the magnitude of the Nursery Industry’s contributions to the state’s economy, which: Gives power to the Nursery Industry when working with local, state and federal policymakers
QUESTIONS?
ocuments how the loss of sales due to plants being added to D the Pest Plant List will impact Tennessee nurseries
Amy Fulcher afulcher@utk.edu
Identifies industry trends that can aid your business projections elps university faculty understand and addresses nursery issues H through educational programs and research
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Watch your inbox for an email from Amy Fulcher for your opportunity to take this survey!
tennessee greentimes SPRING 2020
Susan Schexnayder schexnayder@utk.edu
Industry News
JIMMY DRIVER HONORED as SNA Honorary Member
T
his year’s recipient of the SNA Honorary Member Award is Jimmy Driver, Jimmy Driver Plant Brokerage & Consulting, McMinnville, TN. Jimmy Driver served as President of Middle Tennessee Nursery (1974 – 1975); President of the Tennessee Nursery Association (1984 – 1985); Member of the Board of Governors of the American Nursery Association (1990 – 1993). He was honored as Tennessee Wholesale Nurseryman of the Year in 1992. He has served on various committees of state, regional and national associations. Jim, along with Otis Floyd, led the delegation to facilitate the legislative and funding activities to move the nursery research center to McMinnville – the Otis Floyd Nursery Crop Research Station. Jim also served on the legislative committee of the American Nursery Association. He attended conferences in Washington, DC at the Capitol and the White House. Mr. Driver joined the US Navy at the age of 17 in 1957. He began his nursery experience by selling trees on the side while working other jobs. Living in Chattanooga, and close to
McMinnville, he would take orders and sell trees during the week to neighbors and fellow employees at his other jobs. After several years, he and his family moved back to Smithville. Because there were no nurseries who would sell to the public, Jim started a retail center in the heart of the wholesale nursery industry named Cumberland Nursery in Smithville. From a meager beginning in 1970, the nursery grew to a 150-acre operation with twenty employees, Mr. Driver sold wholesale as well as retail. He was one of the first to grow trees in containers in many sizes. This maintained the operation year around regardless of weather conditions. Raised primarily by his grandparents on a small farm in DeKalb County Tennessee, everything revolved around producing food in order to keep the family going. Jim looks at this time of working with his hands in the dirt as the beginning of his love of farming and working with the ground. In 1995, Jim embarked on a new adventure. He began a new business, Jimmy Driver Plant Brokerage & Consulting. Representing nurseries across several states, he still works full time to this day. He currently lives in McMinnville, TN where the trees are! Jim would like to remember two individuals who were instrumental in his success in the nursery industry: Tommy Henegar and Edward S. Porter, both loved the SNA. The SNA Awards Program is designed to recognize professionals for their distinguished talents, extraordinary service and life achievements, and who have demonstrated their commitment to the Southern Nursery Association and the industry through these annual awards
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Feature Story
The SOUTHERN ROOT KNOT NEMATODE By Amy Dismukes, Nursery Extension Area Specialist, TSU, Otis L. Floyd Nursery Research Center
P
lant parasitic nematodes are tiny, microscopic, “worm-like� animals (Fig. 1) that live in the soil and plant tissues. In Tennessee, the most troublesome species to the nursery industry are those that feed on plant roots and live in the soil. These nematodes can be challenging to diagnose, difficult to control, and can be easily spread from site to site in soil that may be carried on tools, on equipment and tires, on mud-caked boots, and within or on infested plant material. The Southern root knot nematode (RKN), Meloidogyne incognita, is a major pest in nurseries. RKN can infest the roots of many woody ornamentals including, but not limited to, boxwood (Buxus spp.) (Fig. 2), catalpa (Catalpa speciosa), cedar (Cedrus spp.), Japanese quince (Chaenomeles spp.), euonymus (Euonymus spp.), gingko (Ginkgo biloba), Althea (Hibiscus syriacus), hydrangea (Hydrangea macrophylla), Chinese holly (Ilex cornuta), jasmine (Jasmium primulinum), walnut (Juglans spp.), mulberry (Morus spp.), nandina (Nandina domestica), stone fruit (Prunus spp.), fire thorn (Pyracantha spp.), oak (Quercus spp.), and viburnum (Viburnum spp.). Root knot nematodes damage plant roots through their feeding activity, which is achieved by piercing root cells using a needle-like mouthpart called a stylet. Once attached to the root, feeding activity results in gall and clubbed-root formation on root tissues (Fig. 3).
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Fig. 1. Newly hatched (2nd stage) juvenile root knot nematodes (Photo Credit, Alan Windham)
Fig. 2. Field-grown boxwood shrubs infested by root knot nematodes may present symptoms similar to water stress or nutrient deficiency (Photo Credit, A. Dismukes)
Fig. 3. Galled and clubbed root tips caused by root knot nematode feeding on root tissues (Photo Credit, A. Dismukes)
Feature Story Continued
When nematode levels become high enough (Fig. 4), gall induction can disrupt root function. The extent of plant damage depends on the environment, nematode species, populations within the plant following reproduction, and host plant tolerance. Root knot nematodes develop from egg to adult through six life stages that can be completed within 21 to 28 days. RKN deposit eggs in the soil (Fig. 5), and after the eggs hatch, the 2nd-stage juveniles infest root tips. Within the infected root, cells enlarge and galls are formed (Fig. 6). Immature and adult male RKN remain vermiform (worm-like) and will eventually leave the roots. Adult RKN females expand into a swollen, pear shape and remain within the root, depositing eggs into the soil through the root surface. Once in the soil, the reproductive cycle continues until the environment becomes unfavorable. Adult female RKN and root knots are visible without a microscope, however, juveniles and males are too small to be seen without additional magnification.
SYMPTOMS Because above-ground symptoms of RKN activity are not always obvious in colonized plants, infection and reproduction can go undetected. Symptoms of RKN infestation and feeding can be confused with plants that have impaired root function resulting from other causes. Appearance often mimics drought stress, nutrient deficiency, or stress associated with root pathogens. In above ground plant tissues, visible symptoms to the plant include wilting (particularly when soil moisture is adequate), loss of vigor, bronzing and yellowing of leaves (Fig. 7), etc. Plants will produce fewer and smaller leaves and fruits. Plants will not grow as quickly as uninfested plants and may defoliate earlier than normal. Under heavy RKN infestation plants can die. Damage is often worst in warm, irrigated, sandy soils.
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Fig. 4. To see galls on infected plant roots, wash soil or substrate from roots. Root tips may break with rough handling, but galls are not easily rubbed off by hand (Photo Credit, A. Dismukes).
Fig. 5. A mass of root knot nematode eggs being deposited into soil (Photo Credit, Alan Windham)
Fig. 6. A close up of cleaned boxwood roots shows galls formed in response to nematode feeding (Photo Credit, A. Dismukes).
Fig. 7. Bronzing and yellowing of foliage is characteristic of root knot nematode infection on a heavily infected boxwood plant (Photo Credit, A. Dismukes).
Feature Story Continued Injury to infected plant roots can be more difficult to diagnose. In extreme cases, root galls can grow up to 1-inch in diameter on some host plants, but galls are usually much smaller. Unlike nitrogen-fixing nodules on legumes, RKN galls are true
swellings that cannot be rubbed off by hand. In addition to damaging the conductive abilities of infected plant roots, galls can predispose host plants to infection by other soil-borne pathogens, thereby increasing potential losses in susceptible crops.
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tennessee greentimes SPRING 2020
If you believe that your crops may be infected with nematodes, contact the TSU Nursery Research Center in McMinnville, Extension agents, or specialists with the University of Tennessee Soil, Plant & Pest Center. An appropriate specialist can help conduct assays using plant tissue, root, and soil samples to identify and positively confirm nematode presence. The best time to monitor nematodes in soils is immediately before or at crop harvest, when seasonal nematode populations have reached their peak. Samples collected in the spring will normally have reduced levels of nematodes due to unfavorable reproductive conditions, but if damage is severe, may be capable of detecting presence of RKN.
MANAGEMENT and CONTROL
MeMber of
TIFWAY 419
DIAGNOSIS and DETECTION
Once RKN are diagnosed, growers and landscape managers may have several options to assist them in limiting further damage to crops and landscape specimens. Root knot nematode can be difficult to manage long-term with chemical nematicides because nematodes persist in soil and can infect a wide range of host plants. In production systems, fumigants can be applied as pre-plant treatments to reduce populations. To be effective, however, the fumigant must penetrate a large volume of soil. Many fumigants volatilize quickly, so treated soil must be covered to retain the nematicide after application. Nervous system toxicants, like carbamate and organophosphate products, are not toxic to plants and may provide a measure of control against RKN, but these broad-spectrum pesticides are extremely toxic to non-target organisms and also present threats to health of applicators. When misapplied, nervous system toxicants can cause significant damage to the human nervous system. Biological control methods are an important strategy in effective nematode management. There are many kinds of nematophagous (nematode-eating) fungi,
plus beneficial bacterial antagonists that are usually present already within a healthy soil. Some fungal species rely on spores to capture RKN, others have specialized structures that develop on hyphae, while other species directly penetrate nematode surfaces and can parasitize eggs and females. Pasteuria penetrans is a bacterial RKN antagonist that attaches to the cuticle of a juvenile nematode and then consumes it. Although a number of commercial biocontrol agents are available for RKN management, they may not be economically feasible for treating large production areas. To encourage these nematode antagonists in field operations and landscapes, proactive nursery growers and landscape managers should focus on maintaining optimal soil health with high organic content, which tend to have lower RKN populations. Cultural control methods to manage nematode populations are potentially the most successful method for limiting RKN damage. Successful cultural control benefits from careful planning. If the grower can identify an alternative non-host plant species, or a resistant crop that provides a high economic return, crop rotation can be very successful. RKN will increase the damage potential of plants that are water-stressed. Frequent irrigation can also help reduce damage. Populations will still be present but they will cause less damage. Cover crops provide organic matter to soil that will also help to reduce nematode populations. Cover crops can be grown in a fallow year or outside of the normal growing season for nursery crops. Some cover crops are directly antagonistic to nematodes. For example, both sudangrass and marigolds produce chemicals that are toxic to nematodes, while also providing the added benefits of conserving topsoil and improving soil quality. In warm climates and when a field can be removed from cultivation for long periods, flooding and soil solarization have also been used to control nematodes. Finally, peat, aged manure, and composts can be added to manage good soil health. These amendments provide organic matter and are useful for increasing the water and nutrient holding capacity of soils. Taken together, these steps all lessen the impacts of nematode injury.
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Feature Story Continued A combination of management tactics and tools can help reduce RKN to population levels that do not exceed acceptable damage thresholds. It is important to remember that once RKN are present in a soil system, RKN will always be present; eradication efforts will not be successful. Once a susceptible host plant is transplanted and begins to grow in infested soils, however, its roots will support RKN reproduction, which in turn will result in expanding nematode populations and a greater infection rate. In RKN infested habitats, the management goal shifts toward actions that optimize plant health and reduce plant and crop damage from nematodes.
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Braun Horticulture Inc...................................................23 www.braungroup.com
Motz & Son Nursery.......................................................21 www.motzandson.com
Brown’s Nursery..............................................................13
Neely Coble Co...................................Inside Front Cover www.neelycoble.com
Cam Too Camellia Nursery, Inc...................................23 www.camtoocamellia.com Coosa Valley Turf Farms...............................................20 www.coosavalleyturffarms.com D & D Agri........................................................................23 Ditch Witch of Tennessee...............................................7 www.ditchwitchtn.com Fairview Evergreen Nurseries.......................................11 www.fairviewevergreen.com Hidden Valley Nursery, LLC..........................................22 www.hiddenvalleynursery.com John Holmlund Nursery.................................................14 www.jhnsy.com Leading Edge Communications...................................23 www.LeadingEdgeCommunications.com Mid Tenn Turf..................................................................11 www.midtennturf.com
Richey Nursery Company, LLC.......................................7 www.richeynursery.com Smith Seed Services........................................................7 www.smithseed.com Surface Nursery Inc.......................................................15 www.surfacenursery.com Swafford Nursery Inc.......................................................3 www.swaffordnursery.com Tennessee 811................................................................21 www.tnonecall.com Tree Equipment Design, Inc.........................................21 www.treeequip.com The Turfgrass Group........................................................5 www.theturfgrassgroup.com Wellmaster Carts........................................... Back Cover www.wellmaster.ca
ASSOCIATE Cameron Financial Darryl Yochem 3200 West End Ave, Suite 500 Nashville, TN 37203
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SEPTEMBER 10 – 11 Wilson County Exposition Center Lebanon, TN www.tngie.com
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