Brief Summary of Minutes of Annual Meeting

The meeting, which was held in Room 410 of the Plant Biotechnology Building at UTK, was called to order by A. Keinath, Chair, at approximately 9:10 a.m. B. Ownley, local arrangements host, welcomed the attendees and visitors were introduced. Objective 1. The first order of business was to discuss the cooperative project to evaluate new biocontrol agents and materials for control of wirestem on broccoli. Eight treatments were evaluated at five locations (KY, TN-Knoxville, TN-Jackson, AR, and SC) in the fall 2008-winter 2009 test. Three treatments were incorporated into the potting mix: millet seed infested with binucleate-Rhizoctonia (BNR) at 0.56% dry wt., Monarda herbage at 2% dry wt., and BioYield Flowable, a source of plant growth-promoting rhizobacteria, at 0.75 fl oz/1000 plants. Two treatments included seed treated with Beauveria bassiana isolate 11-98 at 1 x 10 7 cfu/seed in a 2% methyl cellulose solution. An untreated control, a fungicide standard (Quadris 2.08F or Terrachlor 75WP), and a treatment of two applications of Actinovate AG (one 1 day after seeding trays and again 1 day before transplanting) were also included. Results were a little disappointing. In SC, only 50% of the plots were infested with Rhizoctonia solani and no effects on disease or yield were noted. In KY, rodents destroyed the test before any data was recorded. In AR, only yield data was recorded. In TN at Knoxville, plants were lost to winter injury before data collection. In TN at Jackson, there was also no disease, but a treatment effect on plant growth was noted: Plants with Beauveria bassiana 11-98 seed treatment + 2% Monarda herbage appeared to grow faster than most other plants and yielded significantly more than all other treatments except the fungicide standard. In subsequent discussions, C. Canaday and B. Ownley reported that changes in the research focus of UT's branch research stations will make continued participation in the broccoli regional research tests more difficult. No test was planned for fall 2009. C. Canaday will see if there's sufficient horticultural data for a journal article in HortTechnology on the effects of the biocontrol treatments on broccoli growth. Meeting attendees then reported on their research related to Objective 1. C. Canaday reported on his research on the effects of potash treatments and seed treatment biocontrol agents on plant stand and yield of soybean. K. Gwinn reported on her research on the volatile components of Monarda herbage, their percentages of total extracted oils, and their EC50 values for R. solani. C. Rothrock reported on his research on Brassica biofumigation comparing use of Brassica napus cv. Bionute (broadcast over cotton fields) to the commercial fumigant Telone. A. Keinath reported on his research on the use of root grafts to control Fusarium oxysporum f. sp. niveum on seedless watermelon. Objective 3. Committee members reported on the results of their evaluation of treatments for recovery of anastomosis groups (AG) of Rhizoctonia solani from soil using two techniques (soil pelleting and toothpick baits) and three media (modified ethanol-potassium nitrate medium [Plant Disease 71:1098-1100; substitute 300 ppm streptomycin and 100 ppm rifampicin for 100 ppm tobramycin and use 2% ethanol instead of 5%], Ko and Hora medium [Phytopathology 61:707-710], and water agar + benomyl + chloramphenicol). M. Elliott found the poorest growth on the water agar and best growth on Ko and Hora medium. B. Ownley also reported best results with Ko and Hora medium. C. Rothrock and A. Keinath reported that the ethanol-potassium nitrate medium was best. Ko and Hora medium was acceptable, but Pythium and Trichoderma contaminants were a problem. C. Rothrocks Ph.D. student plans additional tests with toothpick baits. A. Keinath reported that toothpick isolation was better than soil pellets and better than bean or broccoli seedlings. He found that prochloraz slowed the growth of R. solani from soil and that rifampicin was a suitable substitute for tobramycin. C. Garzon reported that she plans to compare soil pellets versus molecular techniques in her course on soilborne diseases of plants. Members then discussed protocol details for Objective 3. Final protocol details included: 1. Collect soil to a depth of 7.5 cm from five locations per site. Ideally, collect soil from agricultural field site about two weeks after planting, from within the row. 2. Don't store soil. Refrigerate no more than two weeks before assay. 3. Uniformly mix soil and remove large pieces of organic debris (no need to screen soil). Save enough soil for physical (textural) and chemical analysis; air dry this sub-sample. 4. For each sample, fill four 10-cm-diameter plastic, square greenhouse pots 7.5 cm deep with soil. 5. Water soil with tap water until it drains. Wait 24 hours. 6. For three of the pots, place nine white birch toothpicks (flat) vertically in soil to a depth of 5 cm (1 cm remaining above the soil line) about 2.5 cm apart in a 3 x 3 grid in soil in each pot. Do not autoclave toothpicks. 7. With the fourth pot, remove 10 g of soil, dry it for 24 h at 105 C and reweigh for gravimetric water analysis. 8. Place pots with toothpicks in the dark at 22±1 C. 9. After 48 h, remove toothpicks and place on modified ethanol-potassium nitrate medium (see above), 3 toothpicks per plate. Place plates in the dark at 22±1 C. Agri-Mek 0.15EC (abamectin) (5 ppm [0.275 ml per L]) may be added to inhibit mites. 10. Obtain about 500 g of soil from these three pots, spread thin in a tray and autoclave for 20 minutes. Then freeze at -20 C for future shipment to C. Garzon (but do not ship until Garzon makes the request). 11. After 24 to 72 h, record the number of colonies of Rhizoctonia growing from the toothpicks. Collect every suspect Rhizoctonia colony and transfer to full-strength PDA. 12. Save 10 colonies per sample for genetic analysis and anastomosis group determination. Store isolates as colonized agar plugs in sterile deionized water (minimize amount of agar added to storage vials). Store at room temperature. Plans for work under Objective 2 not already mentioned were covered in state reports: Arkansas. C. Rothrock plans to do more R. solani AG-group diagnoses. Oklahoma. C. Garzon reported that she plans to do DNA diversity studies and will use diagnostic primers to test for the presence of Phymatotrichopsis omnivora in asymptomatic hosts. She also will use her Pythium irregulare primers to determine if the pathogen is infesting different commercial nurseries. She will continue her work on the population biology of Sclerotinia minor and is trying to identify the peanut genes for resistance to S. minor. She also will continue to investigate the microbial populations in suppressive and non-suppressive Ecuadorian soils for Phytophthora infestans. Business Meeting. A. Keinath, chair, called the business meeting to order at 5:40 p.m. C. Garzon was nominated as secretary for 2010. The nomination was seconded and passed unanimously. C. Garzon, who had to depart the meeting earlier in the day, subsequently accepted the secretary nomination via email correspondence with A. Keinath. C. Rothrock offered to host the next meeting in Fayetteville, AR, in November 2010. The offer was accepted by all those present. Members were asked to send state reports to A. Keinath before Christmas break. The meeting was adjourned at 5:50 p.m. Members traveled home on November 15. Respectfully submitted, C. Canaday, Secretary