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United States Department of Agriculture

Agricultural Research Service

Title: Formulation of the Biocontrol Fungus Cladorrhinum Foecundissimum to Reduce Damping-off Diseases Caused by Rhizoctonia Solani and Pythium Ultimum

Authors
item Lewis, Jack
item Larkin, Robert

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 11, 1998
Publication Date: N/A

Interpretive Summary: The implementation of effective biocontrol of plant diseases depends on the development of appropriate formulations of microbes. The research of this report falls within the ARS Strategic Plans for biocontrol technology in commercially-grown plants. Isolates of the novel biocontrol fungus Cladorrhinum foecundissimum (Cf) were amended to Rhizoctonia solani (R-23) - infested soilless mix as bran, alginate prill and flour/clay granular formulations. Bran formulations reduced damping-off of eggplant and pepper caused by R-23. After 4 weeks of growth, plant stands (> 80%) were comparable to those in the noninfested controls. The bran preparations also reduced saprophytic growth of the pathogen. Added to soilless mix, alginate prill of six biocontrol isolates (Cf-1,2,3,4,5,6) reduced damping-off of eggplant caused by R-23. Alginate prill with Cf-1 and Cf-2 biomass also reduced damping-off of eggplant and pepper caused by other isolates (195, NG-2, DPR-1) of R. solani. For the first time, it was shown that alginate prill of C. foecundissimum (Cf-1,2,3) reduced damping-off of eggplant and pepper caused by Pythium ultimum (PuZ3). The treatments also reduced populations of P. ultimum in the soilless mix. Extruded flour/clay granules containing biomass of Cf-1 and Cf-2 reduced damping-off of eggplant and pepper. However, only the Cf-2 treatments resulted in stands (> 80%) equal to those in the noninfested controls for the crops after 4 weeks of growth. This research benefits scientists and private industry interested in commercial development for use against plant pathogens as a substitute for synthetic chemicals.

Technical Abstract: Five isolates of Cladorrhinum foecundissimum, added to soilless mix as bran preparations, reduced damping-off of eggplant and pepper caused by Rhizoctonia solani (R-23). After 4 weeks of growth, plant stands (> 80%) were comparable to those in the noninfested controls. The bran preparations also reduced saprophytic growth of the pathogen. Added to soilless mix, alginate prill with biomass of six biocontrol isolates (Cf-1, 2, 3, 4, 5, 6) reduced (P < 0.05) damping-off of eggplant caused by R. solani, but only the prill with Cf-1 and Cf-2 biomass yielded plant stands comparable to that in the noninfested control. As with the bran preparations, there was an inverse correlation between saprophytic growth and eggplant stand with the alginate prill. Alginate prill with Cf-1 and Cf-2 biomass also reduced damping-off of eggplant and pepper caused by other isolates (195, NG-2, DPR-1) of R. solani. For the first time, it wa shown that alginate prill of C. foecundissimum (Cf-1, 2, 3) reduced damping-off of eggplant and pepper caused by Pythium ultimum (PuZ3). Extruded flour/clay granules containing biomass of Cf-1 and Cf-2, added to R. solani-infested soilless mix, reduced damping-off of eggplant and pepper. The influence of bran and alginate prill of Cf-1 and Cf-2 on the spatial spread of R. solani to incite damping-off of eggplant showed that prill with Cf-1 and Cf-2 and bran with Cf-2 were equally effective in reducing the spread of the pathogen from the point source of the inoculum to the center of the flats.

Last Modified: 7/22/2014
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