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United States Department of Agriculture

Agricultural Research Service

Title: Damping-off Diseases Caused by Rhizoctonia Solani and Pythium Ultimum As Affected by Alginate Prills with Biomass of Biocontrol Fungi and Various Organic Food Bases

Authors
item Lewis, Jack
item Lumsden, Robert
item Locke, James

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 1995
Publication Date: N/A

Interpretive Summary: Formulation and delivery systems, which are commercially feasible for biocontrol agents to suppress soilborne plant pathogens are technologically necessary to develop. Inexpensive, readily-available food base carriers (bran, corn cobs, peanut hulls,soy fiber, castor pomace, cocoa hulls, chitin) were incorporated into alginate prill with fermentor-produced biomass of Trichoderma hamatum (TRI-4) and Gliocladium virens (Gl-21) to evaluate their effectiveness on damping-off of zinnia caused by Rhizoctonia solani and Pythium ultimum and of cotton caused by R. solani. Also, the effect of the prills on proliferation of Gl-21 and TRI-4 in soilless mix and soil and on survival and saprophytic growth of R. solani was studied. Although all prills controlled diseases of zinnia, prill with bran, soy fiber, castor pomace, and chitin resulted in plant stands (>75%) comparable to that in pathogen-free soilless mix. Prills with all food bases gave cotton stands in soil similar to that in pathogen-free soil. All prills allowed proliferation of Gl-21 and TRI-4 in soil and there was no correlation between proliferation and disease control. Prills containing TRI-4 and bran and chitin were the most effective in the reduction of survival and saprophytic growth of R. solani. The results are significant because they demonstrate that wide variety of agricultural wastes can be utilized as food base carriers for the delivery of biocontrol fungi to reduce pathogen inoculum and diseases they cause on economic crops. Consequently, industry has a wide latitude in accessible food base carriers to use in the formulation of alginate prills for disease control.

Technical Abstract: Alginate prill were formulated consisting of fermentor-produced biomass of isolates of the biocontrol fungi Gliocladium virens (=Trichoderma virens) (Gl-21) and Trichoderma hamatum (TRI-4) and various food bases (bran, corn cobs, peanut hulls, soy fiber, castor pomace, cocoa hulls, chitin). These prills were evaluated for their effect on damping-off of zinnia caused by Rhizoctonia solani and Pythium ultimum and damping-off of cotton caused b R. solani. In addition, the influence of the prills on proliferation of Gl-21 and TRI-4 in soilless mix and soil and on survival and saprophytic growth of R. solani were evaluated. In later studies, isolates of T. harzianum (Th-58), T. viride (T-1-R9), and G. virens (Gl-3) were formulated also. Alginate prills with Gl-21 biomass and most food bases significantly prevented damping-off of zinnia in soilless mix caused by R. solani and P. ultimum. The prills with bran, soy fiber, castor pomace, and chitin resulted in stands similar to that in the noninfested control. In soil, prills with all the food bases and TRI-4 biomass prevented disease and gave stands comparable to, or better than that (55%) in the noninfested control soil. Prills with all the food bases resulted in a proliferation of Gl-21 in soilless mix. Prills with food bases and TRI-4 biomass reduced the survival of R. solani in infested beet seed to less than 30%. Bran and chitin were the most effective food bases. Alginate prills with TRI-4 biomass and bran reduced saprophytic growth of R. solani in soil the best. Prills with food bases and TRI-4 were more effective than those with Gl-21. With bran, soy fiber, and chitin, prills and biomass of Th-58 and T-1-R9, Th-58 was almost as effective as TRI-4 regardless of food base in the prill.

Last Modified: 7/31/2014
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