Management of Southern Root-Knot Nematode in Appling County, Georgia D.S. Curry1and R.C.Kemerait21University of Georgia Coop. Ext., Baxley, GA 315191 and 2Dept. of Plant Pathology, University of Georgia, Tifton, GA, ABSTRACT 31793. RESULTS and DISCUSSION (continued)Management of the plant-parasitic nematodes is of critical 4. Use of PHY 367 did not result in a decrease of late-season rootimportance throughout Georgia and annually costs producers galling nor did it result in decline of late-season nematodemore than $100 million. The southern root-knot nematode populations as compared to PHY 375. PHY 367 out-yielded PHY(Meloidogyne incognita) is especially important in Appling County 375 by 191 lb/A lint.where sandy soils and long-term cotton production allow fordamaging populations of this organism to develop quickly. The 5. Use of Telone II resulted in numeric increase in yield and gin turn-objective of this study was to determine appropriate management out and numeric decline in late-season root damage. Telone II wasstrategies for management of M. incognita with the use of a the most important production practice in this study to be of benefitpartially resistant variety (PHY 367B2RF), a seed treatment to the grower.nematicide (AVICTA Complete Cotton) and Telone II. Thepopulation of M. incognita in the field used in this study was as 6. Efficacy of AVICTA Complete Cotton to manage nematodes in thismuch as 6X the economic threshold level for the southern root- A cotton field in Appling County planted to a heavy cover-crop of rye was fumigated study was tied to the area of the field where evaluated. Whereknot nematode in Georgia. Little difference was noted between with Telone II, 4 gal/A, weeks prior to planting. A good stand was established nematode populations were moderate, the treatment appeareddamage to the PHY 367 versus PHY 375. Yield for resistant PHY despite the heavy residue. Fumigation process was difficult because cover crop had appropriate. not been “killed”.367 treated with AVICTA was 191 lb/A greater than where PHY375 was planted. Fumigation with Telone II in conjunction with Figure 1. M. incognita, juveniles/100cc soil at harvest MATERIALS and METHODSeither variety resulted in a numeric reduction in root-damage and 1. A replicated field trial was established on the Jeff Deen farm in Appling 800 NSan increase in yield (413 lb/A). SPECIAL NOTE: County, Georgia in 2011. This field has a history of losses to M. incognita. For Figures 1 and 2 two 600 sets of data are presented 2. The experimental design was a factorial randomized complete block with for PHY 375 + AVICTA 400 and PHY 367 + AVICTA. 3 replications. Treatments included combinations of PHY 367B2RF and Originally the second set 200 PHY375B2RF (seed treated with AVICTA Complete Cotton) with and was to be over-treated without Telone II (1,3-dichloropropene, 4 gal/A). Fumigation with occurred 0 with VYDATE CLV. As PHY367+AVICTA PHY375 + AVICTA this did not happen, the weeks prior to planting. The cotton crop was planted on 7 Jun and plots were simply PHY367+AVICTA + Telone PHY375 + AVICTA+ Telone harvested on 15 Nov. duplicates of other PHY367 +AVICTA PHY375+AVICTA treatments. The data are presented separately here 3. Vydate CLV, planned as a third treatment to compliment use of AVICTA Figure 2. Galls per gram of root at harvest as results from this study Complete Cotton, was not applied. Thus, there were two sets of plots clearly document that treated with AVICTA but not Vydate. Yield was not determined for the 40 efficacy of seed-treatment nematicides is closely tied second set of these pots. 30 to the magnitude of A A populations of parasitic 20 nematodes in a field. 4. Data collected included soil sampling to determine nematode B B B B Coincidentally, the second populations, end-of-season root-damage ratings, and yield (non- 10 set of seed treatments replicated). was placed in severely 0 infected areas of the field. A root system damaged by southern root-knot PHY367+AVICTA PHY375 + AVICTA nematodes (above, at right). In picture at right, PHY367+AVICTA + Telone PHY375 + AVICTA+ Telone collecting soil samples after harvest to determine PHY367 +AVICTA PHY375+AVICTAend-of-season levels of plant parasitic nematodes. Figure 3. Gin Turn-out as determined by the Figure 4. Lint Yield based upon gin turnouts reported by 1048 Satilla Cotton Gin Satilla Cotton Gin INTRODUCTION % Lint 1,600 1,501 Yield/lbs Per acreAppling County lies in the Coastal Plain of southeastern 45% 41% 1,400 1,279Georgia. Cotton is an important crop for growers in this county 40% 36% 31% 1,200 1,088and management of plant-parasitic nematodes is especially 35% 1,000 30%important as soils in the county are typically very sandy. 25% 800 600Meloidogyne incognita, the southern root-knot nematode, is the 20% 400 15%most important nematode affecting cotton in this region. 10% 200Growers have historically used aldicarb, Temik 15G, to manage 5% 0 PHY 375 + Telone + PHY 367 + Avicta PHY 375 + Avictaboth thrips and nematodes; however the loss of Temik 15G 0% PHY 375 + Telone + Avicta PHY 367 + Avicta PHY 375 + Avicta Avictaearly in 2011 necessitated additional field trials to determine Data reported in Figures 3 and 4 are based upon combined harvest of all plots of a givenrefined opportunities for control of nematodes in Appling County. treatment. Plots for the treatment PHY 367 + AVICTA + Telone II were not harvested due RESULTS and DISCUSSION to error. Seed-cotton yields for plots treated with Telone II were more than 300 lb/A 1. The field trial at the Jeff Deen farm is pictured in photos above just greater than were yields in plots that were not fumigated. However, based upon reportedThe objective of this study was to compare the performance of a prior to harvest. Plots fumigated with Telone II are obvious; however it is gin turn-out, reported lint differences are much greater than anticipated. ALSO: Data forcotton variety with known partial-resistance to the root-knot the AVICTA-ONLY treatments does not include the second set of plots where damage not possible to differentiate plots planted to PHY 367B2RF versus PHY from nematodes was most severe.nematode (PHY 367B2RF) treated with AVICTA Complete 375B2RF.Cotton to a popular variety without resistance (PHY 375B2RF),also treated with AVICTA Complete Cotton. Additionally plots 2. From nematode samples collected after harvest (Figure 1) it is clear Special Thanks to: Jeffplanted to each variety as above and fumigated with Telone II (4 that the populations of root-knot nematodes in the field far exceed the Deen (right), Greg Black,gal/A), were compared to non-fumigated plots. It was hoped that economic threshold established for Georgia (100 juveniles/100cc soil). Lamar Turner, Satilla Cottonthe results from this study would give growers in eastern Despite use of a resistant variety (PHY 367B2RF), high counts were Gin, Dow AgroSciences, andGeorgia better idea strategies to integrate nematode resistance found in all treatments. Phytogen Cotton Seed.and nematicides into their cotton production practices. 3. Plots originally to be treated with Vydate CLV following emergence were used as a second set of AVICTA Complete Cotton treatments. This proved fortuitous as areas planted were more affected by nematodes than the first set.