2007 Annual Report
1a.Objectives (from AD-416)
Optimize agronomic systems and environmental practices, including fertilization and rotation that minimize inoculum potential of Aspergillus flavus and other mycotoxin-producing fungi while maximizing corn yield and profits in the Mid-south USA. Gain an understanding of the role of crop management practices on the ecology of Aspergillus flavus and aflatoxin contamination in order to optimize the application of competitive exclusion products. Develop economical biologically-based strategies, including antagonists from soil fungi and bacteria, microbial competitors and antagonists, and natural compounds from biological sources, to minimize mycotoxins and their respective fungi in corn, and continue ecological studies on Aspergillus populations under various management strategies, e.g., rotations, tillage, and cover crops, and herbicide-resistant crops. Evaluate insect-resistant and susceptible maize lines for insect damage and aflatoxin and fumonisin contamination. Evaluate corn accession for aflatoxin resistance. Develop isolines with stable resistance and susceptibility. Cooperate with industry in using molecular markers to develop resistent inbreds/hybrids.
1b.Approach (from AD-416)
Evaluate potassium fertility as a means to decrease mycotoxins. Evlaluate corn maturity as a management practice to avoid heat and/or drought stress and mycotoxins. Evaluate double-cropped corn for mycotoxin contamination. Evaluate corn-soybean rotation to reduce fungal inoculum. Characterize population dynamics of Aspergillus propagules in soil, air, insects and corn at various ontogeny in BT and conventional corn. Compare efficacy of non-toxigenic A. flavus strains as biocontrol agents. Optimize surfactant concentration and formulation for improvement of efficacy of non-toxigenic strains. Determine efficacy of Pichia anomala to control aflatoxin and fumonisin. Identify and characterize bacteria from corn field soils as biocontrol agents of Aspergillus and Fusarium. Isolate and identify factors in corn-earn-worm-resistant corn silks for control of insects and mycotoxins.
This project is one year old, started December 28, 2005, replacing project 6402-42000-002-00D. Progress and accomplishments related to the previous project were reported separately last year. To date, this project is proceeding as anticipated. The initial focus was on planning and establishing field experiments with other lab and greenhouse projects to follow as the year progressed. In spring of 2007, all our field experiments were planted successfully, preparing fungal, yeast, and bacterial inoculum to be used as biological agents to manage mycotoxin contamination in corn were successfully prepared. However, application was delayed because of an unusually wet July 2007 and has altered the time of inoculum application.
Research directed toward environmental manipulation to minimize aflatoxin and optimize yield in corn is proceeding. This includes experiments on potassium fertility and aflatoxin incidence. Comparison of growth and development of mid-season corn hybrids with full season hybrids is under way. Double cropping short season maturing corn hybrids in the Mid South is in its second growing season. The third growing season of corn-soybean crop rotation experiment is progressing. The impact on fungal inoculum source of Aspergillus contamination in non-Bt and Bt corn is planted in 2007 for the second season.
Research on biological and chemical methods for controlling aflatoxin in corn is progressing well in 2007. Field studies are continuing using the pin-bar inoculation technique to characterize the colonization patterns of corn by various strains of A. flavus including Alfa-Guard, K49 and CT3 as biocontrol agents. Field studies optimizing formulation for improvement of delivery of non-toxigenic A. flavus strains is in its second season. The potential for using the yeast, Pichia anomala, and two bacteria isolated from corn field soil, to control aflatoxin and fumonisin on corn have also been initiated in field studies.
Research to evaluate insect-resistant and susceptible maize lines for insect damage and aflatoxin and fumonisin contamination were not met. Because of poor corn growing conditions in a winter nursery at Ponce, Puerto Rico, 2006, a sufficient quantity of corn seed was not available to produce the quantity of silks needed for testing. A good seed increase though was achieved in 2007. Sufficient silks were produced and chemical fractions are currently being made and tested.
Some of the research on this project is being done in cooperation with scientists at other institutions. Research in objective 1 is being conducted by Louisiana State University under a Specific Cooperative Agreement between ARS and LSU. Separate reports summarize work completed under these agreements (subordinate project 6402-42000-003-01S and 6402-42000-003-03S). A scientist at University of Bologna, Italy, is cooperating on research listed in objective 2 under a Non-Funded Cooperative Agreement between ARS and University of Bologna. A separate report summarizes work completed under this agreement (subordinate project 6402-42000-003-04N).
This is a relatively new project. All experiments contracted within it are underway and have yet to be completed to a point that significant accomplisments can be claimed.
5.Significant Activities that Support Special Target Populations
|Number of invention disclosures submitted||2|
|Number of patent applications filed||2|
|Number of non-peer reviewed presentations and proceedings||24|
|Number of newspaper articles and other presentations for non-science audiences||3|
Abbas, H.K., Bruns, H.A., Abel, C.A. 2006. Influence of Messenger on Corn and Mycotoxins in Mississippi. Plant Health Progress. doi:10.1094/PHP-2006-1016-03-RS.
Bruns, H.A., Abel, C.A. 2007. Effects of Nitrogen Fertility on Bt Endotoxin Levels in Corn. Journal of Entomological Science. 42(1):35-34.
Ranezabu, M., Shier, W.T., Abbas, H.K., Tonos, J.L., Baird, R.E., Sciumbato, G. 2007. Production of (-)-Botryodiplodin, but not Phaseolinone, by the Soybean Charcoal Rot Disease Fungus Macrophomina phaseolina in Mississippi. Journal of Natural Products. 70:128-129.
Moore, S.H., Damonn, K.E., Mascagni, Jr, H.J., Abbas, H.K. 2006. Emerging Technologies for Reducing Aflatoxin in Corn. Louisiana Agriculture. 49(4):23-24.
Bruns, H.A., Pettigrew, W.T., Meredith Jr, W.R., Stetina, S.R. 2007. Corn Yields Benefit in Rotation with Cotton. Crop Management.