Progress 09/01/10 to 08/31/13
Outputs
Target Audience: This project reached an estimated of more than 2,000 persons over a period of three years through a variety of outreach and academic activities. Target audiences included rice producers, rice millers, crop consultants, county extension agents, industry representatives, extensional specialists, scientific communities and the general public. These audiences were located in the southern rice-producing states with the majority of them being in Texas. Changes/Problems: Merle M. Anders at the Rice Research Center, University of Arkansas participated in conducting the field trials at Stuttgart, AR. What opportunities for training and professional development has the project provided? This project has provided one-on-one mentoring, two workshops and four seminars in support to train two PhD graduate students, one master student, two undergraduate students and one postdoctoral researcher. This project also has provided five field tours, one workshop, and three conferences to educate rice crop consultants, rice farmers and industry representatives in disease identification, epidemiology and management. How have the results been disseminated to communities of interest? Results of this project were disseminated to rice producers, rice millers, crop consultants, county extension agents, industry representatives, extensional specialists and the general public through a variety of outreach activities. These activities included Annual Rice Field Days (2011, 2012 and 2013), County Certified Education Advisors Training (2013), Annual Texas Rice Days (2011 and 2012), Annual Texas Plant Protection Conferences (2011 and 2012), Southeast Texas Rice Symposium (2012), Texas Department of Agriculture Pest Inspectors Workshop (2011), and talks and presentations at other local extension meetings. Results of this project also were delivered to national and international scientific communities through the Annual Meetings of the American Phytopathological Society (2011, 2012 and 2013), the Rice Technical Working Group Conference (2012), the 2nd Asian PGPR Conference (2011), U.S. Rice Breeding Conference (2012), invited seminars and article publications in popular newsletters, and professional and scientific journals. Summary reports of field trials were published in the Plant Disease Management Reports (PDMR), and placed on the website maintained by the Texas A&M AgriLife Research and Extension Center at Beaumont. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Sheath blight is the most serious disease in rice, causing millions of dollars of losses annually. Famers heavily rely on fungicides and apply more than 1 million pound of them annually to rice. Rice farmers are in need of sustainable and environmentally-friendly management alternatives. This four-state project has developed biologically-based management strategies for integrated control of sheath blight by using brassica biofumigation cover crop, biocontrol bacterial agent and their combinations with a rate-reduced fungicide. Results of this project provide new sheath blight management tools for rice farmers, especially ratoon (second) crop famers, while reducing use of fungicides by 50%. Reducing the usage of harmful fungicides can help to reduce potential risks to human health and the environment. This project has reached more than 2,000 persons including rice producers through a variety of outreach and academic activities. Objective 1: Screen for promising brassica biofumigation crops in the greenhouse. Thirty-seven brassica species and other related plants were evaluated on agar plates for their volatile antagonistic activity on mycelial growth of Rhizoctonia solani. Ten brassica species significantly inhibited mycelial growth in the evaluation. These 10 brassica species were further tested for their ability to reduce the populations of R. solani in potted soils from TX, MS and AR in the greenhouse. Mustard cv. Caliente 199 was among the most effective brassica species that reduced soil populations of the fungus. Mustard Caliente 199 was selected for further greenhouse and field evaluations. A greenhouse trial was conducted in soils collected from TX, MS and AR. Fresh aboveground biomass of mustard Clientele 199 was incorporated into R. solani-infested soil at 0, 0.2, 0.4, 0.8, 1.6, and 3.2% (wt/wt) and Cocodrie was seeded into treated soil. Amended rates of 0.2, 0.4, 0.8, 1.6, and 3.2% were all effective in reducing soil populations of R. solani. However, the amendment rate of 0.2% was less effective. An amended rate response curve was established to define the relationships between brassica plant biomass amendment rate and R. solani population reduction. Objective 2: Evaluate the efficacy of biocontrol agents in combination with reduced fungicide rates to suppress sheath blight in the greenhouse. More than 70 plant growth-promoting rhizobacteria (PGPR) strains were screened for their antagonistic activity against R. solani on agar plates. They were also examined for their ability to inhibit lesion development on detached leaves of rice. Twenty PGPR strains that performed well in these tests were selected and evaluated for suppressing sheath blight in rice seedlings in the greenhouse. The Bacillus subtilis strain MBI600 was identified as the most promising biocontrol agent. In addition, strain MBI600 was evaluated for its compatibility with eight fungicides commonly used for rice and found to have good tolerance to all the fungicides including azoxystrobin. A greenhouse trial was conducted as a 5 x 7 factorial with the five concentrations (0, 103, 106, 109, and 1011 CFU/ml) of strain MBI600 and seven rates (0, 17, 33, 50, 67, 83 and 100% of the recommended rate, 0.16 kg a.i./ha) of azoxystrobin for their efficacy of control of sheath blight. A corresponding dose response curve was developed. Disease severity decreased with the increase of the concentration of strain MBI600 and with the increase of the rate of azoxystrobin. A synergetic effect was observed when strain MBI600 was used in combination with azoxystrobin. When strain MBI600 concentration increased to 109 CFU/ml, its combinations with 50% or more of the recommended rate of azoxystrobin resulted in 100% control of the disease. Strain MBI600 at 109 CFU/ml in combination with azoxystrobin at 50% of the recommended rate was selected as the optimum combination for field evaluations. Objective 3: Evaluate the efficacy of integrating biofumigation cover crop, biocontrol agent, rate-reduced fungicide, and partial resistant cultivar to control sheath blight in the field. A total of six field trials were conducted in R. solani-infested field plots in TX, AR and MS in 2011, 2012 and 2013 to evaluate the efficacy of brassica cover crop, strain MBI600 and azoxystrobin for control of sheath blight. The trials were conducted as a split-split plot design with two main plot treatments (mustard Caliente 199 cover crop and fallow), two subplot treatments (Cocodrie and Presidio) and five sub-subplot treatments (strain MBI600 at 109 CFU/ml, strain MBI600 at 109 CFU/ml plus azoxystrobin at 0.08 kg a.i./ha, azoxystrobin at 0.08 kg a.i./ha, azoxystrobin at 0.16 kg a.i./ha, and unsprayed control). The brassica crop was planted at 11.2 kg/ha in early fall and incorporated into soil before winterkill. Rice seeds were treated with strain MBI600 prior to seeding. At the panicle differentiation (PD) and boot stages, plots were sprayed with strain MBI600 and azoxystrobin, respectively. In Texas, the trials also were conducted on the ratoon crop. Since no fungicides are labeled for use on the ratoon crop, only strain MBI600 was applied to rice plants at PD. Soil populations of R. solani were quantified prior to brassica planting, incorporating, and rice seeding. Sheath blight severity was assessed near maturity. Plots were harvested using a plot combine and grain yield determined. In TX and AR, sheath blight severity was lower in plots seeded to brassica cover crop than in plots left fallow in each year. However, the brassica cover crop treatment did not significantly increase grain yield compared to the fallow treatment. Similarly, strain MBI600 alone reduced disease severity but did not increase yield. Combinations of the brassica cover crop with azoxystrobin at 0.08 kg a.i./ha, strain MBI600 with azoxystrobin at 0.08 kg a.i./ha, or all these three treatments resulted in a consistent and significant improvement in disease reduction and yield increase compared with the non-treated control. These combinations achieved similar efficacy as did azoxystrobin applied at the full rate (0.16 kg a.i./ha). In MS, strain MBI600 applied alone or in combination of azoxystrobin at 0.08 kg a.i./ha was effective in increasing yield on Cocodrie. For the ratoon crop trials in TX, combined use of the brassica cover crop, strain MBI600 and azoxystrobin at 0.08 kg a.i./ha significantly reduced sheath blight severity in each year and improved grain yield in one year. Pathogen populations were generally reduced in brassica-incorporated plots compared to fallow plots. Results of this study indicate that combined use of brassica cover crop and/or PGPR strain MBI600 with a rate-reduced fungicide can offer new management options for sheath blight while reducing the use of fungicide in rice by 50%. Objective 4: Disseminate the results of research and new management options for sheath blight to rice producers and other clientele. This project has reached an estimated of more than 2,000 persons, including rice producers, rice millers, crop consultants, county extension agents, industry representatives, extensional specialists and the general public, through a variety of outreach and academic activities. In summary, all the four objectives of this project have been accomplished. This research has successfully identified the best performing brassica cover crop and biocontrol agent and developed integrated sheath blight management options of using brassica cover crop, biocontrol agent and their combinations with a dose-reduced fungicide for rice producers, especially ratoon crop producers. These new management options are compatible to current pest management practices and can be adopted in the southern rice-producing. PGPR strain MBI600 is the active ingredient in the biopesticide Integral®. Integral® and Mustard ‘Caliente 199’ are available commercially.
Publications
- Type:
Other
Status:
Published
Year Published:
2013
Citation:
Anders, M.M., Zhou, X.G., Liu, G., and Jia, Y. 2013. Evaluation of brassica cover crop and PGPR strain for suppression of sheath blight of rice in Arkansas, 2012. Plant Disease Management Reports 7: FC048.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Handiseni, M., Zhou, X.G., and Y.-K. Jo. 2013. Impact of Brassica juncea cover cropping on rice sheath blight disease incidence, severity and yield. Phytopathology 103:S1.5.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Kumar, K.V.K., Yellareddygari, S.KR., Reddy, M.S., Kloepper, J.W., Lawrence, K.S., Miller, M.E., Sudini, H., Reddy, E.C.S., Zhou, X.G., and Groth, D.E. 2013. Ultrastructural studies on the interaction between Bacillus subtilis MBI 600 (Integral�) and the rice sheath blight pathogen, Rhizoctonia solani. Afr. J. Microbiol. Res. 7(19):2078-2086.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G. 2013. Rice disease control research. Fort Bend County Certified Education Advisors Training. Sep. 11, 2013. Beaumont, Texas, USA.
- Type:
Other
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G., and G. Liu. 2013. Efficacy of combined use of brassica biofumigant crop and PGPR strain for managing sheath blight in rice, 2012. Plant Disease Management Reports 7: FC049.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G., Liu, G., Anders, M., Allen, T.W., Kloepper, J.W., Reddy, M.S., Jia, Y., Lu, S., Jo, Y.-K., and Way, M. 2013. Integrated control of rice sheath blight using beneficial bacteria and fungicide in the South. The 2013 Beaumont and Eagle Lake Rice Field Days. Beaumont and Eagle Lake, Texas, USA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G., Liu, G., Anders, M.M., Allen, T.W., Kloepper, J.W., Reddy, M.S., Jia, Y., Lu, S., Jo, Y.-K., and Way, M. 2013. PGPR and its combined use with fungicide for control of rice sheath blight in the southern U. S. Texas Rice XIII:17.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G., Liu, G., Anders, M.M., Jia, Y., Allen, T. W., Lu, S., Reddy, M.S., and Kloepper, J.W. 2013. Multistate evaluation of PGPR strain MBI600 and its combined use with azoxystrobin for control of sheath blight in rice. Phytopathology 103:S2.168.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Zhou, X.G., Liu, G., Handiseni, M., Anders, M. M., and Jia, Y. 2013. Brassica cover cropping for management of sheath blight of rice. Texas Rice XIII:21-22.
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Progress 09/01/11 to 08/31/12
Outputs
OUTPUTS: A greenhouse experiment was conducted to establish an amended rate response curve that defines the relationships between brassica plant biomass amendment rate and sheath blight suppression. The experiment was conducted in natural soils from Texas, Arkansas and Mississippi. Fresh aboveground biomass of mustard Clientele 199 harvested from greenhouse-grown plants were incorporated into soil artificially infested with Rhizoctonia solani at 0, 0.2, 0.4, 0.8, 1.6, and 3.2% (wt/wt, approximately equivalent to 0, 4.5, 9, 18, 36 and 72 tons of dry aboveground biomass per hectare). After 2 weeks following incorporation, Cocodrie was seeded into treated soil in plastic pots. Soil populations of R. solani were determined using the toothpick method prior to brassica incorporation and rice seeding. Aboveground biomass of rice plants, number of tillers per plant, and disease severity were assessed at the termination of the experiment. A Texas field trial was conducted in 2010 and 2011 at Beaumont to evaluate the efficacy of combined use of plant growth-promoting rhizobacteria (PGPR) strain MBI600 and reduced-rate azoxystrobin for control of sheath blight in rice. This trial consisted of six treatments: 1) Strain MBI600, 2) Strain MBI600 plus azoxystrobin (Quadris 2.08SC) at 0.08 kg a.i./ha, 3) Strain MBI600 plus azoxystrobin at 0.16 kg a.i./ha, 4) azoxystrobin at 0.08 kg a.i./ha, 5) azoxystrobin at 0.16 kg a.i./ha, and 6) Unsprayed control. Strain MBI600 at 10^9 CFU/ml was applied to seeds and rice plants at the panicle differentiation (PD) stage. Azoxystrobin was applied at boot. R. solani inoculum was introduced into plots at PD. A multistate field trial was conducted in 2012 in Texas, Arkansas and Mississippi to evaluate the effects of individual and combined effects of brassica cover crop, PGPR strain MBI600, rate-reduced azoxystrobin and cultivar resistance on sheath blight in rice. This trial was conducted as a split-split plot design with two main plot treatments (mustard Caliente 199 cover crop and fallow), two subplot treatments (Cocodrie and Presidio) and five sub-subplot treatments (strain MBI600, strain MBI600 plus azoxystrobin at 0.08 kg a.i./ha, azoxystrobin at 0.08 kg a.i./ha, azoxystrobin at 0.16 kg a.i./ha, and unsprayed control). The trial was conducted in the field that had been naturally infested with R. solani prior to planting of the brassica. Brassica crop was planted at 11.2 kg/ha in early fall and incorporated into soil before winterkill. Seed of Cocodrie and Presidio (susceptible and moderately susceptible to sheath blight, respectively) was treated with strain MBI600 prior to seeding. At the PD and boot stages, plots were sprayed with strain MBI600 and azoxystrobin, respectively. Management of weeds, insects and irrigation followed local recommendations. Soil populations of R. solani were quantified using the toothpick method prior to brassica planting, incorporating, and rice seeding in brassica-treated and fallow soils. For both Texas and multistate field trials, sheath blight severity was rated 1 week before harvest and grain yield was determined at maturity. PARTICIPANTS: Mere Anders at the Rice Research Center, University of Arkansas participated in conducting the field trial at Stuttgart, AR. This project partially supported to train two PhD graduate students, two undergraduate students and one postdoctoral researcher. TARGET AUDIENCES: The results of this research project were delivered in a timely manner to rice producers, crop consultants, county extension agents, chemical industry representatives, scientific societies and the general public through a variety of outreach and academic activities. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Efficacy of mustard Caliente 199 for reducing R. solani was confirmed in soils from Texas, Arkansas and Mississippi under controlled environments. An amendment rate response curve was further established for mustard Caliente 199 in soils from these three states in the greenhouse. From the amendment rate response curve, 0.4% (wt/wt, approximately equivalent to 9 tons of dry aboveground biomass per hectare) of the brassica was the optimum amendment rate in terms of pathogen population reduction and rice plant growth improvement. Amended rates of 0.2, 0.4, 0.8, 1.6, and 3.2% (wt/wt, equivalent to 4.5, 9, 18, 36 and 72 ton/ha) were all effective in reducing soil populations of R. solani compared to the non-amended control. However, the amendment rates less than 0.4% (9 ton/ha) were less effective. Amendment rates of 0.8% (18 ton/ha) or above produced a reduction in rice plant biomass weight and tillers per plant, which probably was caused by phytotoxicity. In the Texas field trial, strain MBI600 applied to seed and rice at PD resulted in a significant reduction in sheath blight severity over the untreated control in each of two years. Combined use of PGPR strain MBI600 with azoxystrobin at 0.08 kg a.i./ha further reduced disease severity. The efficacy of this combined treatment was comparable to that of azoxystrobin at 0.16 kg a.i./ha (the full recommended rate). The combined treatment tended to have higher grain yield than the untreated control and have similar yield to azoxystrobin at 0.16 kg a.i./ha. In the multistate field evaluation, the results of the trial in Texas, which were the only data available at the time of reporting, indicated that sheath blight severity was lower in plots seeded to brassica cover crop than in plots left fallow the spring. Strain MBI600 significantly reduced disease severity in plots either incorporated with brassica or left fallow when compared to the unsprayed control. Combined use of brassica cover crop and PGPR achieved similar efficacy in reducing sheath blight as did azoxystrobin at 0.16 kg a.i./ha. Pathogen populations were generally reduced in brassica-incorporated plots compared to fallow plots. It was expected that the results of the field trials from Arkansas and Mississippi would be available by the end of the 2012 cropping seasons. In summary, our preliminary data suggest that the integrated approach of using brassica biofumigation cover cropping, PGPR biocontrol agent and rate-reduced azoxystrobin can provide a novel practical means to minimize yield losses caused by sheath blight while reducing fungicide use on rice. This project served more than 800 persons including rice farmers, crop consultants, county extension agents, chemical industry representatives, other professionals and the general public through annual field days, Texas Rice Festival, Southeast Texas Rice Symposium, and Rice Production Conference. Results were delivered to national and international scientific communities through annual meetings of professional societies, Proceedings of 34th Rice Technical Working Group, Annual Texas Plant Protection Conference, and publications in extension newsletters and scientific journals.
Publications
- Handiseni, M., Zhou, X.G., and Jo, Y.-K. 2012. In vitro screening of plant materials as biofumigants for the management of Rhizoctonia solani in rice. Phytopathology 102: (in press).
- Kuma, K.V.K., Reddy, M.S., Yellareddygari, S. KR., Kloepper, J.W., Lawrence, K.S., Zhou, X.G., Suddin. H., and Miller, M.E. 2012. Efficacy of Bacillus subtilis MBI 600 (Integral) against sheath blight caused by Rhizoctonia solani and on growth and yield of rice. Rice Science 19 (1): 55-63.
- Zhou, X.G., and Liu, G. 2011. Plant growth-promoting rhizobacteria: A new rice disease management option. The 64th Beaumont Rice Field Day. Beaumont, Texas, USA.
- Zhou, X.G., and Liu, G. 2012. Efficacy of combined use of brassica biofumigant crop and PGPR strain for managing sheath blight in rice. 2011. Plant Disease Management Reports 6: FC056.
- Zhou, X.G., Kumar, K.V.K., Reddy, M.S., Kloepper, J.W., Jia, Y., Allen, T.W., Lu, S., and Way, M.O. 2012. PGPR: A novel strategy for sheath blight control and fungicide use reduction in rice. Page 17 in Proc 34th Rice Technical Working Group (RTWG). Hot Springs, Arkansas, USA.
- Zhou, X.G., Liu, G., Kloepper, J.W., and Reddy, M.S. 2012. Integrated management of rice sheath blight using brassica biofumigation cover crop and beneficial bacteria. Texas Rice XII (Special Section):25-26.
- Zhou, X.G., Liu, G., Kloepper, J.W., and Reddy, M.S. 2012. Use of brassica biofumigation cover crop and plant growth promoting rhizobacteria to manage sheath blight of rice. Phytopathology 102: S4.144.
- Zhou, X.G., Liu, G., Kloepper, J.W., Reddy, M.S., Kumar, K.V.K., and S. Zhang. 2012. Field evaluation of Bacillus PGPR strains and fungicides for control of sheath blight in rice, 2011. Plant Disease Management Reports 6: FC054.
- Zhou, X.G., Way, M.O., Kumar, K.V.K., Reddy, M.S., Kloepper, J.W., and Zhang, S. 2011. PGPR: a new strategy to reduce fungicide use and manage sheath blight in rice. Page 45 in 23rd Annual Texas Plant Protection Conference. Bryan, TX, USA.
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Progress 09/01/10 to 08/31/11
Outputs
OUTPUTS: A series of in vitro, greenhouse and field evaluations were conducted to identify the plant growth-promoting rhizobacteria (PGPR) and the brassica crops that are most effective in suppressing sheath blight caused by Rhizoctonia solani in rice. More than 70 PGPR strains that were previously demonstrated growth promotion in other plants and antibiosis against other plant pathogens were screened for their antagonistic activity on mycelial growth of R. solani, germination of sclerotia and hyphal growth of germinated sclerotia on agar plates. They were also examined for their ability to inhibit lesion development on detached leaf blades of rice and to enhance vigor of seedlings. Twenty PGPR strains that performed well in these tests were selected and evaluated for suppressing sheath blight in rice seedlings in the greenhouse. One Bacillus subtilis strain, MBI600, was among the most effective PGPR strains screened. MBI600 was evaluated for its potential mechanisms involved in disease suppression and its growth promoting activity on four rice cultivars. MBI600 also was evaluated for its compatibility with eight commonly-used fungicides at the concentrations of 100 to 1,000 ppm. MBI600 and its combined use with azoxystrobin at different rates were further determined in rice seedlings under greenhouse conditions to develop a dose response curve that can determine the optimum concentrations of MBI600 and azoxystrobin for control of sheath blight. Thirty-seven brassica species and other related plants were evaluated on agar plates for their volatile antagonistic activity on mycelial growth of R. solani. Ten brassica species that significantly inhibited the pathogen in the evaluations were further tested for their ability to reduce the populations of R. solani and disease severity in soils from AR, MS and TX. Mustard cv. Caliente 199 that was shown to be among the most effective brassica species in these tests was selected to determine for an amended rate response curve. Field observations and trials were conducted to determine the optimum times for seeding and incorporating mustard cv. Caliente 199 in TX, AR and MS. Three dates for seeding the brassica in the fall and winter of 2010 and two dates for seeding the brassica in the spring of 2011 were conducted in TX. The activities and part of the results of this research project were timely delivered to rice producers, crop consultants, county extension agents, chemical industry, academic societies and the general public through annual Beaumont and Eagle Lake field days, Texas Rice Festival, Southeast Texas Rice Symposium, Texas Department of Agriculture pest inspection personnel training, Annual meeting of the American Phytopathological Society, Proceedings of 2nd Asian PGPR Conference, U.S. Rice Breeding Conference, and publications of outreach and professional newsletters and scientific journals. PARTICIPANTS: Kuma, K.V.K. actively participated in the research activities of this project. He conducted lab and greenhouse evaluations screening for effective biocontrol agents and their combined use with fungicides during his PhD research program at the Department of Entomology and Plant Pathology, Auburn University, Auburn, AL. Dr. Kumar now is a faculty member of the Acharya N G Ranga Agricultural University, Hyderabad, India. This project partially trained two PhD graduate students, one undergraduate student and one postdoctoral researcher. TARGET AUDIENCES: The activities and part of the results of this research project served more than 750 persons including rice farmers, crop consultants, county extension agents, chemical industry representatives, other professionals and the general public through annual field days, Texas Rice Festival, Southeast Texas Rice Symposium,and Texas Department of Agriculture pest inspection personnel training. The results of this research also were timely delivered to national and international academic societies through the Annual meeting of the American Phytopathological Society, Proceedings of 2nd Asian PGPR Conference, U.S. Rice Breeding Conference, and publications of professional newsletters and scientific journals. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The B. subtilis PGPR strain MBI600 was identified as the most promising biocontrol agent for control of rice sheath blight. MBI600 was one of the screened PGPR strains that showed greatest ability to inhibit vegetative growth and germination of sclerotia of R. solani and reduce disease severity in the detached leaf and greenhouse-grown seedling bioassays. These biocontrol effects are primarily involved in the production of siderophores (low molecular weight iron-chelating compounds) by MBI600, an effective antibiosis mechanism against R. solani and many other plant pathogens. Seed treatment with this bacterial strain at 10^6 CFU/ml or above significantly improved seed emergence and promoted plant growth of four rice cultivars (Cocodrie, Catahoula, Neptune and Trenasse). MBI600 was compatible with fungicides commonly used for rice sheath blight management. The strain had strongly tolerance to benomyl, hexaconazole, mancozeb, propiconazole, tricyclazole and validamycin, and good tolerance to azoxystrobin and carbendazim. A dose response curve that adequately described efficacy of combined use of MBI600 and azoxystrobin for sheath blight reduction was developed from greenhouse bioassays. MBI600 at 10^9 CFU/ml when used in combination with azoxystrobin at 50% or above of the recommended rate (0.18 kg a.i./ha) completely controlled sheath blight. MBI600 at 10^9 CFU/ml in combined use with azoxystrobin at 50% of the recommended rate thus is selected as the optimum combination for future field evaluations. Mustard cv. Caliente 199 was identified as the most promising brassica crop that was effective in inhibiting growth of R. solani and reducing soil populations of the fungus in the lab and greenhouse bioassays. Based on field observations and the results of field trials, optimum dates to seed mustard cv. Caliente 199 were in early to middle October in TX, and in late September to early October in AR and MS. Seeding rates could range from 5.5 to 11 kg/ha. The brassica crop could be plowed into soil before winterkill. In conclusion, we have successfully identified the best performing biocontrol agent and its combined use with a dose-reduced fungicide as well as the effective brassica crop that can be used in TX, AR and MS in year 1 of this project. The performance of these three disease control components for disease control and yield increase will be evaluated under field conditions in TX, AR and MS in year 2 of this project. The new rice sheath blight management strategies developed from this project have the high potential of being directly adopted for rice production in the South. Both the biocontrol agent MBI600, the active ingredient in the biopesticide Integral, and the biofumigant brassica cover crop cv. Caliente 199 are commercially available products.
Publications
- Kuma, K.V.K., Reddy, M.S., Kloepper, J.W, Lawrence, K. S., X. G. Zhou, Groth, D.E., Zhang, S., Raju, M.R.B., Raju, S. K., Fernando, D., Sudini, H., Du, B., and Miller, M. E. 2011. Commercial potential of microbial inoculants (PGPR) for sheath blight management and yield enhancement of rice. Chapter 9 In: D. K. Maheshwari (ed.), Bacteria in Agrobiology: Crop Ecosystems. Springer-Verlag Berlin Heidelberg Dordrecht London New York, P. 237-264.
- Kuma, K.V.K., Reddy, M.S., Kloepper, J.W, Lawrence, K. S., Yellareddygari, S. KR., Zhou, X. G., Sudini, H., Reddy, E.C.S., Groth, D.E., and Miller, M. E. 2011. Screening and selection of elite plant growth promoting rhizobacteria (PGPR) for suppression of Rhizoctonia solani and enhancement of rice seedling vigor. Journal of Pure and Applied Microbiology 5(2):641-651.
- Kuma, K.V.K., Reddy, M.S., Kloepper, J.W., Yellareddygari, S. KR., Lawrence, K. S., Zhou, X. G., Suddin, H., Miller, M. E., Appa, R. P., Surendranatha, R.E.C., Niranjana, S.R., and Chandra, N.S. 2011. Plant growth-promoting activities of Bacillus subtilis MBI 600 (Integral) and its compatibility with commonly used fungicides in rice sheath blight management. International Journal of Microbiology Research 3(2):120-130.
- Kuma, K.V.K., Reddy, M.S., Yellareddygari, S. KR., Kloepper, J.W., Lawrence, K.S., Zhou, X.G., Suddin. H., and Miller, M. E. 2011. Efficacy of Bacillus subtilis MBI 600 (Integral) against sheath blight caused by Rhizoctonia solani and on growth and yield of rice. Rice Science 18: (Accepted).
- Kuma, K.V.K., Reddy, M.S., Yellareddygari, S.KR., Kloepper, J.W., Lawrence, K.S., Zhou, X.G., Suddin, H., and Miller, M. E. 2011. Evaluation and selection of elite plant growth-promoting rhizobacteria for suppression of sheath blight of rice caused by Rhizoctonia solani in a detached leaf bio-assay. International Journal of Applied Biology and Pharmaceutical Technology 2(1):488-495.
- Kumar, K.V.K., Yellareddygari, S.KR., Reddy, M.S., Kloepper, J.W., Sudini, H., Zhou, X.G., Reddy, E.C.S., Yuan, Z.-L., Yang, Z.-L., Wang, Q., Du, B., Reddy, B.R., and Reddy, B.V.B. 2011. Screening of PGPR strains for suppression of rice sheath blight caused by Rhizoctonia solani under greenhouse conditions. Page 281-287 in Proc 2nd Asian PGPR Conference. Beijing, China.
- Kumar, K.V.K., Yellareddygari, S.KR., Reddy, M.S., Kloepper, J.W., Sudini, H., Zhou, X.G., Reddy, E.C.S., Yuan, Z.-L., Yang, Z.-L., Wang, Q., Du, B., Reddy, B.R., and Reddy, B.V.B. 2011. Evaluation of combined efficacy of Bacillus subtilis MBI 600 and azoxystrobin in managing rice sheath blight caused by Rhizoctonia solani. Page 270-280 in Proc 2nd Asian PGPR Conference. Beijing, China.
- Kumar, K.V.K., Yellareddygari, S.KR., Reddy, M.S., Kloepper, J.W., Sudini, H., Zhou, X.G., Reddy, E.C.S., Yuan, Z.-L., Yang, Z.-L., Wang, Q., Du, B., Zhang, S., Reddy, B.R., and Reddy, B.V.B. 2011. Overview of commercial potential of plant growth-promoting rhizobacteria (PGPR) in the USA. Page 539-546 in Proc 2nd Asian PGPR Conference. Beijing, China.
- Zhou, X.G., Reddy, M.S., Kloepper, J.W., and Zhang, S. 2010. Biologically-based integrated management of rice sheath blight. Texas Rice X(4) (Special Section):20.
- Zhou, X.G., Reddy, M.S., Kloepper, J.W., Kumar, K.V.K., and Zhang, S. 2011. Field evaluation of a beneficial Bacillus strain for biocontrol of sheath blight in rice. Phytopathology 101:S204.
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