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United States Department of Agriculture

Agricultural Research Service

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Location: Sustainable Agricultural Systems Laboratory

2008 Annual Report

1a. Objectives (from AD-416)
Evaluate the impact of soil environmental factors on the behavior (including disease suppression and colonization of plant surfaces) of biological control agents (BCAs). Evaluate the impact of interactions resulting from the combination of BCAs with other biologically or chemically based control measures on the performance of BCAs. Develop strategies to enhance compatibility between BCAs combined with other BCAs or cover crops in biologically based disease control strategies directed at controlling Pythium ultimum, Phytophthora capsici, and Meloidogyne incognita on cucumber and pepper. Develop strategies for combining chemical pesticides with biologically based disease control methods in integrated pest control strategies directed at controlling P. ultimum, P. capsici, and M. incognita on cucumber and pepper.

1b. Approach (from AD-416)
Use basic microbiology techniques to determine soil factors that negatively impact performance of biological control agents. Use techniques from molecular biology, biochemistry, and basic microbiology to identify genes to use as reporters for environmental conditions that negatively impact biological control performance. Multi-disciplinary collaboration in growth chamber and greenhouse studies will determine impacts of cover crops and chemical controls on performance of biological control agents.

3. Progress Report
Four subobjectives of the Project Plan were scheduled to be worked on during this annual report cycle. For three of these subobjectives, studies were to be initiated to determine 1) the impact of soil texture on suppression of Phytophthora capsici by biological control agents, 2) the impact of soil texture on suppression of Pythium ultimum by the biocontrol bacterium Pseudomonas fluorescens Pf-5, and 3) the impact of soil texture on colonization of roots by P. fluorescens Pf-5. Soils with varying texture have been identified at the Beltsville Agricultural Research Center for use in work detailed under these three subobjectives. Additionally, isolates of Trichoderma virens have been identified that suppress P. capsici on bell pepper in a single soil type. These biological control agents can now be used in these studies. For the fourth subobjective, the metabolic activity of P. fluorescens Pf-5 in various soils was to be studied. A plasmid was constructed that allows determining the metabolic activity of bacterial biocontrol in soils. In addition, this plasmid was used to demonstrate that various soil environmental factors can influence the metabolic activity of biocontrol bacteria. The proposed research is applicable to the NP308 Action Plan under Component 1: Pre-Plant Soil Fumigation Alternatives. The proposed work directly addresses Problem Statement 1A: Development of New Technologies for Alternatives and Integration into Commercial Crop Production Systems Currently Dependent upon MB Soil Fumigation.

4. Accomplishments

Review Publications
Baker, C.J., Mock, N.M., Roberts, D.P., Deahl, K.L., Hapeman, C.J., Schmidt, W.F., Kochansky, J.P. 2007. Interference by morpholine ethanesulfonic acid (MES) and related buffers in phenolic oxidation by peroxidase. Biochemical and Biophysical Research Communications. 43:1322-1327.

Tondje, P., Roberts, D.P., Bon, M., Widmer, T., Samuels, G.J., Ismaiel, A.A., Begoude, A.D., Tchana, T., Nyemb-Tshomb, E., Ndoumbe-Nkeng, M., Bateman, R., Fontem, D., Hebbar, K.P. 2007. Isolation and identification of mycoparasitic isolates of trichoderma asperellum with potential for supression of black pod disease of cacao in cameroon. Biological Control. 43:202-212.

Janisiewicz, W.J., Pereira, I., Almeida, M.S., Roberts, D.P., Wisniewski, M.E., Kurtenbach, E. 2008. Improved biocontrol of fruit decay fungi with Pichia pastoris recombinant strains expressing Psd1 antifungal peptide. Postharvest Biology and Technology. 47:218-225.

Last Modified: 06/24/2017
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