Brief Summary of Minutes of Annual Meeting

Accomplishments/Outcomes: Objective 1. Examine commercial and non-commercial biocontrol agents for use as seed treatments, in-furrow treatments or as potting mix amendments. The first regional trial of biocontrol agents and amendments for control of wire stem of broccoli (Rhizoctonia solani) was conducted at five sites in four states in 2007. At Jackson, TN (Canaday), all materials reduced the incidence of Rhizoctonia root rot or Pythium root rot compared to the untreated control and plant growth-promoting rhizobacteria (PGPR) were equal to the fungicide standard for disease control with no adverse effects on growth or yield. In eastern TN (Ownley), broccoli seed treated with Beauveria bassiana 11-98 (1,000,000 spores/seed), followed by planting into potting mix containing 2% bioactive dried Monarda herbage resulted in significantly greater head size and yield weight than the standard fungicide treatment (etridiazole soil treatment and thiram seed treatment) or other treatments evaluated. In South Carolina (Keineth), application to potting mix of Monarda herbage (2% w/w) and BioYield Flowable increased broccoli plant height at 50 days after transplanting compared with the pathogen-infested control. Terraclor increased the number of marketable heads per plot compared with the infested control. In Arkansas (Rothrock), no differences were found in number of healthy plants, plant height or leaf length. The regional trial was planted again in the fall of 2008 at the five sites. The eight treatments had no effect on transplant growth; an untreated control, a fungicide standard, PGPR, a binucleate Rhizoctonia sp., a commercial preparation of Streptomyces lydicus (WYEC 108), a seed treatment with Beauveria bassiana (Bb11-98), and Monarda herbage alone and in combination with Bb11-98. After transplanting in TN (Canaday), the Monarda herbage plus Bb11-98 combination increased plant growth more than any single biocontrol agent. In South Carolina (Keineth), wirestem incidence averaged 7% in noninfested plots and over 36% in plots infested with 15 sclerotia of Rhizoctonia solani AG-4 per kilogram soil. In infested plots, only azoxystrobin fungicide, which was applied to soil at transplanting, reduced wirestem compared with the nontreated infested control. Wirestem incidence did not differ among treatments in noninfested plots. Sites in Kentucky (Seebold) and Arkansas (Rothrock) in 2008 were infested, but incidence of disease was low and no significant differences were found among any of the treatments. Other biological control studies were conducted by individual project members. A trial conducted in KY (Seebold) found Bioten, a commercial formulation containing Trichoderma harzianum and T. viride, significantly reduced Phytophthora blight, caused by Phytophthora capsici, on summer squash when applied to soil via drip irrigation (60% reduction over the untreated control), while Ridomil Gold reduced incidence by at least 90% compared to the untreated control. In TN (Ownley), integration of Beauveria (B. bassiana 11-98 or BotaniGard) seed treatments and RootShield (Trichoderma) potting mix treatment provided mixed results on improvement of growth variables of tomato seedlings in soil infested with Rhizoctonia solani or Pythium myriotylum. Growth was greater with thiram seed treatment, followed by B. bassiana 11-98 seed treatment in one Rhizoctonia trial for most variables, but shoot weight was improved by the combination of Beauveria seed treatments and RootShield in the second trial. In the first Pythium trial, shoot height, and leaf number were greater than the untreated control for seed treatments with BotaniGard, B. bassiana 11-98 and thiram. Stem diameter was greatest for plants from BotaniGard seed treatment. In the second Pythium trial, shoot weight was greatest with the individual treatments of Root Shield and thiram seed treatment. In LA (Padgett), the efficacy of several commercial fungicides and one biological fungicide was evaluated on foliar, pod, and stem diseases on soybean. Foliar treatments were applied during R3 or R3 and R5. Foliar diseases did not develop to appreciable levels during the growing season, however, pod diseases were prevalent late season. Percent defoliation and pod diseases did not differ among treatments. Yields were greater for the treatments Ballad Plus at 2.0 qt/A tank mixed with 3.0 fl oz of Headline and 0.5 qt/A tank mixed with 6.0 fl oz of Headline than the non-treated control. In FL (Elliot), container-grown mexican fan palm (Washingtonia robusta) and queen palm (Syagrus romanzoffiana) transplanted into a field nursery having phosphorus (P)-sufficient and P-deficient soils were treated at the time of planting with four commercial microbial inoculants (each containing arbuscular mycorrhizal fungi, either alone or with other microbial components or fertilizers), two fertilizers, or nothing (control). None of the treatments improved growth over the control in the P-deficient soil. In the P-sufficient soil, none of the microbial inoculants improved growth over that of similarly fertilized non-inoculated palms. Discrepancies were observed regarding non-mycorrhizal fungi and bacteria present in the microbial inoculant products from the product labels. In TN (Canaday), response to Bacillus subtilis (MBI600) when added to fungicide seed treatments for control of seedling diseases of spring-planted snap beans varied with the cultivar used. Adding B. subtilis to a seed treatment of fludioxonil + mefenoxam increased stand loss and lowered yield with Carlo but reduced stand loss and increased yield with Tapia. Adding B. subtilis to a seed treatment of trifloxystrobin + metalaxyl increased stand loss and lowered yield of Carlo but decreased stand loss and increased yield of Tapia. Ashy stem blight of summer-planted snap beans was best controlled and highest yields obtained when an in-furrow spray of boscalid was combined with seed treated with Captan or Captan plus B. subtilis. Potash fertilizers, seed treatments, and in-furrow fungicide sprays were evaluated for control of charcoal rot of soybean (Macrophomina phaseolina). The highest soybean yield was obtained with a seed treatment of Captan plus B. subtilis. Objective 2. Examine the effect of cultural practices on soilborne pathogens and plant growth. In FL (Elliot), bermudagrass root (2 sites, one each in SC and FL) and bentgrass root (2 sites, one each in NC, AL) microflora in sand-based putting greens were examined by analyzing over 9000 randomly selecting bacterial colonies using gas chromatography for analysis of fatty acid methyl ester profiles (GC-FAME). The two dominant genera in both bentgrass and bermudagrass rhizospheres were Bacillus and Pseudomonas, with Bacillus dominant in bermudagrass and Pseudomonas dominant or equal to Bacillus in bentgrass. Other genera that comprised at least 1% of the isolates at all four sites were Clavibacter, Flavobacterium and Microbacterium. Arthrobacter also comprised a significant portion of the bacterial isolates in the bentgrass rhizosphere, but not the bermudagrass rhizosphere. Overall, there were 40 genera common to all four sites. At the species level, there were five that comprised at least 1% of the isolates at each location; B. cereus, B. megaterium, C. michiganensis, F. johnsoniae and P. putida. In IA(Loynachan), a large diversity of mycorrhizal fungi was documented in 8 soils of 4 soybean fields. Large variability exists within a single soil within a field. The composition of individual species varied within soil samples collected 3 m apart. Five species (Glomus. claroideum, G. etunicatum, G. mosseae, G. viscosum, and Paraglomus occultum) were detected in all samples collected. Cultural practices, including raised planting beds composed of wood chips or pine bark mulch, and soil amendment of cow compost to promote biological activity or sulfur to lower pH, were evaluated at five sites for disease management of Phytophthora root rot of Fraser fir (Abies fraseri) grown for Christmas tree production on disease conducive, infested soils in four western NC counties (Benson with Brantlee Ricther, PhD Thesis, and Kelly Ivors, Asst. Prof.). Mulches established increased levels of bacterial and fungal populations, total microbial activity, and cellulase activity, relative to underlying soil. Total microbial activity and cellulase activity remained elevated in mulches, relative to soil treatments, through the first two growing seasons. Mulched plots showed significantly reduced disease at three of five sites through the third growing season, but mortality rates were high across treatments. Possible mechanisms of control in the raised beds include improved drainage and suppression of sporangia production by Phytophthora spp., as well as biological control by cellulose-degrading microbes in the wood chips that will produce cellulase and degrade Phytophthora propagules surviving in soil. Laboratory assays are being conducted to determine if cellulase levels in mulches similar to those observed in the field trials is sufficient to inhibit growth of P. cinnamomi. Cover crops were examined for disease suppression in South Carolina and Arkansas. An on-farm trial was done in SC (Keineth) to evaluate the effects of cover crops and fumigants on Fusarium wilt and yield of seedless watermelon. The two fumigants, 67% methyl bromide-33% chloropicrin and Telone-C35, both combined with hairy vetch (Vicia villosa), were more effective than hairy vetch or rye alone or fallow at increasing yield. Methyl bromide-chloropicrin was more effective at reducing symptoms than Telone C-35. In AR (Rothrock), a Brassica winter cover crop of Indian mustard cv. Fumus was compared with the chemical Telone II and a fallow control in cotton fields having seedling diseases and severe reniform or root-knot nematode infestations. Brassica amendments were observed to reduce seedling root and hypocotyl disease symptoms. Brassica amendments also reduced early season galling from the root-knot nematode similar to the Telone treatment. Brassica treatments improved cotton yield over the control and were similar or greater than the Telone treatment in both the root-knot and reniform nematode infested locations. Brassica amendments including biomass of Brassica juncea cv. Fumus, specifically bred for high levels of glucosinolates, B. napus cv. Jetton, and B. juncea cv. Bionute also significantly reduced disease symptoms and recovery of Rhizoctonia solani from petunia and impatiens. Brassica crops were not significantly different from each other. Rate of Brassica application had the greatest impact on disease symptom reduction and reducing Rhizoctonia solani isolation, with a rate of 3000 g fresh above-ground biomass/square m being more effective than lower rates. In TN (Canaday), the effects of reduced rate fungicides combined with acibenzolar-S-methyl (a SAR inducer) on the incidence of timber rot (Sclerotinia sclerotiorum) and buckeye rot (Phytophthora nicotianae) affecting eight tomato cultivars were evaluated. No significant effects on these soilborne diseases were noted. However, it was shown that routine fungicide sprays may be applied at 1/3 the normal rate in combination with the SAR inducer without significant yield loss or loss in disease control efficacy. The percentage of culled fruit was lowest with 1/3 rate fungicides plus the SAR inducer. Objective 3. Examine the genetic diversity of Rhizoctonia solani between natural ecosystems and agricultural ecosystems. Rhizoctonia solani was isolated from seedlings and soil from cotton producing states participating in the National Cottonseed Treatment Program in 2008. Isolates were characterized using the anastomosis technique. AG 4, AG 7, and AG 11 were found on cotton from different states suggesting a diversity of R. solani is present across the country. Binucleate Rhizoctonia spp. were found in many of the samples. Outputs: Papers were published on the taxonomic diversity of rhizosphere bacteria associated with golf course putting greens, double stranded RNA viruses in Rhizoctonia solani, the biological control agent Beauvaria bassiana, and the use of Brassica amendments. Reports were published on the regional studies using biological control agents for the control of wirestem, caused by Rhizoctonia solani, on broccoli. A new peer-reviewed video (Soil Fungi) has been made available through the MicrobeLibrary from the American Society of Microbiology. A soil biology educational website containing video of important soil organisms including mycorrhizae and their activities has been maintained (http://www.agron.iastate.edu/~loynachan/mov/). Activities: Biological control of wirestem on broccoli, caused by Rhizoctonia solani, was evaluated at five locations (KY, TN-Knoxville, TN-Jackson, AR, and SC) in 2007 and 2008. Field trials are being planned for the 2009 season based on the results from previous tests. Biocontrol trials on impatiens and tomato are being discussed to see if regional evaluations can be expanded to other vegetables and an ornamental crop in 2009. A regional evaluation of techniques for isolation of Rhizoctonia solani from soil with different cropping histories is being planned for 2009. Analyses of recovered isolates of R. solani by anastomosis groups (AG) and other techniques will allow the diversity of the pathogen to be examined based on geography and cropping history.

Books/Book Chapters Charlton, N.D., Tavantzis, S.M. and Cubeta, M.A. 2008. Detection of double stranded RNA viruses in the soil fungus Rhizoctonia solani, In Plant Pathology Techniques and Procedures, Chapter 14, pp. 171-182. Eds. R. Burns, Humana Press, 2nd Edition, Tocawa, NJ. Referred Journal Articles Charlton, N.D., Carbone, I., Tavantzis, S.M., and M.A. Cubeta. 2008. Phylogenetic relatedness of the M2 double stranded RNA in Rhizoctonia fungi. Mycologia 100:555-564. Elliott, M.L., McInroy, J.A., Xiong, K, Kim, J.H., Skipper, H.D., and Guertal, E.A. 2008. Taxonomic diversity of rhizosphere bacteria in golf course putting greens at representative sites in the southeastern United States. HortScience 43:514-518. Ferrucho, R.L., Zala, M., Zhang, Z., Cubeta, M.A., Garcia-Dominguez, C., and Ceresini, P.C. 2008. Highly polymorphic in silico-derived microsatellite loci in the potato-infecting fungal pathogen Rhizoctonia solani anastomosis group 3 from the Colombian Andes. Molecular Ecology Resources (In Press). Leckie, B. M., B. H. Ownley, R. M. Pereira, W. E. Klingeman, and C. J. Jones. 2008. Effects of Beauveria bassiana (Balsamo) Vuillemin mycelia and metabolites incorporated into synthetic diets on larval Helicoverpa zea. Biocontrol Sci. Technol.18: 697-710. Ling, K. S., Kousik, C. S., and Keinath, A. P. 2008. First report of Southern blight on bottle gourd (Lagenaria siceraria) caused by Sclerotium rolfsii in South Carolina. Plant Dis. 92:656. Njoroge, S. M. C., Riley, M. B., and Keinath, A. P. 2008. Effect of incorporation of Brassica spp. residues on population densities of soilborne microorganisms and on damping-off and Fusarium wilt of watermelon. Plant Disease 92: 287-294. Ownley, B. H., M. R. Griffin, W. E. Klingeman, K. D. Gwinn, J. K. Moulton, and R. M. Pereira. 2008. Beauveria bassiana: endophytic colonization and plant disease control. J. Invertebra. Pathol. 98: 267-270. Abstracts Bartz, F.E., Danehower, D.A., Tavantzis, S.M., and Cubeta, M.A. 2008. Carbon metabolism and plant growth regulation: the influence of quinic acid on phenylacetic acid production and pathogenic activity of Rhizoctonia solani AG-3. Proc. 4th International Rhizoctonia Symposium, Berlin, Germany (Abstract). Bartz, F.E., Tavantzis, S.M., Danehower, D.A., and Cubeta, M.A. 2008. Influence of quinic acid catabolism on the production of the plant growth regulator phenylacetic acid by Rhizoctonia solani AG-3. Inoculum 59:19 (Supplement to Mycologia, Abstract). Bartz, F.E., Tavantzis, S.M., Danehower, D.A., and Cubeta, M.A. 2008. Influence of quinic acid catabolism on the production of the plant growth regulator phenylacetic acid by Rhizoctonia solani AG-3. Phytopathology 98:S18 (Abstract). Charlton, N.D., Carbone, I., Tavantzis, S.M., and Cubeta, M.A. 2008. Evolutionary history and population genetics of the M2 double-stranded RNA of Rhizoctonia solani anastomosis group 3. Proc. 4th International Rhizoctonia Symposium, Berlin, Germany (Abstract). Copes, W.E., Rinehart, T. A., Toda, T., and Cubeta, M.A. 2008. Rhizoctonia species associated with bark media and plant strata of container-grown azalea. Proc. 4th International Rhizoctonia Symposium, Berlin, Germany (Abstract). Cubeta, M.A., Dean, R. A., Bayman, P., Jabaji, S., Neate, S., Nolte, P., Tavantzis, S.M., Toda, T. Vilgalys, R., Federova, N., and Nierman, W.C. 2008. Whole genome sequencing of the soil fungus Rhizoctonia solani AG-3. Inoculum 59:21 (Supplement to Mycologia, Abstract). Gomaa, N. M., Rothrock, C. S., and Jia, Y. 2008. Sequence variation of the rDNA internal transcribed spacer (ITS) region among isolates of Rhizoctonia solani. Proceedings of the 4th International Symposium on Rhizoctonia. Greenberg, W., L. Hartley, T. Loynachan, D. Lindbo, and S. Schultz. 2008. Maintaining and updating the SSSA K-12 education website. 531-7 Agron. Abstracts, Madison. Kaye, A., Parks, L., Kennedy, G., Shew, B.B., Carbone, I., Cubeta, M.A., and Moyer, J.W. 2008. Population genetics of Tomato Spotted Wilt Virus on peanut in North Carolina and Virginia. Phytopathology 98:S79 (Abstract). Ownley, B. H., M. M. Dee, and K. D. Gwinn. 2008. Effect of conidial seed treatment rate or entomopathogenic Beauveria bassiana 11-98 on endophytic colonization of tomato seedlings and control of Rhizoctonia disease. Phytopathology 98:S118. (Abstract.) Richter, B. S., Benson D. M., and Ivors, K. L. 2008. Cellulase activity and microbiology of cultural systems for Phytophthora root rot control in Fraser fir. Phytopathology 98:S132 (Abstract). Toda, T., Upchurch, R.G., and Cubeta, M.A. 2008. Development of an Agrobacterium-based transformation system for Rhizoctonia solani. Proc. 4th International Rhizoctonia Symposium, Berlin, Germany (Abstract). Toda, T., Strausbaugh, C., Vilgalys, R., and Cubeta, M.A. 2008. Characterization of a basidomycete fungus from sugarbeet. Inoculum 59:59 (Supplement to Mycologia, Abstract). Peer-Reviewed Journal Reports Canaday, C.H., 2008. Effects of cultivar, a SAR inducer, and PGPR on foliar diseases and yields of staked-tomato, 2007. Plant Disease Management Reports 2:V029. Canaday, C.H. and A. Mengistu, 2008. Effects of seed treatments, in-furrow sprays, and herbicide timing on charcoal rot of soybean, 2007. Plant Disease Management Reports 2:FC014. Canaday, C.H. and A. Mengistu, 2008. Effects of directed fungicide sprays and potash form on charcoal rot of soybean, 2007. Plant Disease Management Reports 2:FC015. Canaday, C.H., Ownley, B.H., Gwinn, K.D., Rothrock, C.S., Keinath, A.P., and Seebold, K.W. 2008. Effects of biocontrol agents versus a fungicide on growth, yield, and diseases of broccoli in Tennessee, 2007-2008. Plant Disease Management Reports 2:V145. Keinath, A.P., V.B. DuBose, A.W. Lassiter, C.H. Canaday, C S. Rothrock, B.H. Ownley, 2008. Evaluation of biological controls against wirestem of broccoli in South Carolina, 2007. Plant Disease Management Reports 2:V152. Ownley, B.H., Gwinn, K.D., Dee, M.M., Canaday, C.H., Keinath, A.P., Rothrock, C.S., and Seebold, K.W. 2008. Effects of biocontrol agents on growth, yield, and root disease of broccoli in East Tennessee, 2007-08. Plant Disease Management Reports 2:V155. Seebold, K.W., Holdcroft, A.M., and Dixon, E. 2008. Effect of potassium phosphite and fungicides on Phytophthora crown and fruit rot of summer squash, 2007. Plant Disease Management Reports 2:V005. Other Loynachan, T. E. 2007. Endomycorrhizae [Online]. Available at http://www.microbelibrary.org/asmonly/details.asp?id=2504&Lang=. MicrobeLibrary. American Society for Microbiology. Loynachan, T. E. 2007. Nematode-trapping fungi [Online]. Available at http://www.microbelibrary.org/asmonly/details.asp?id=2506&Lang=. MicrobeLibrary. American Society for Microbiology. Loynachan, T. E. 2007. Ectomycorrhizae [Online]. Available at http://www.microbelibrary.org/asmonly/details.asp?id=2508&Lang=. MicrobeLibrary. American Society for Microbiology. Loynachan, T. E. 2008. Soil fungi [Online]. Available at http://www.microbelibrary.org/asmonly/details.asp?id=2801&Lang=. MicrobeLibrary. American Society for Microbiology.