ARS | Publication request: Comparative Biocontrol Efficacies of "p" and "q" Strains of Trichoderma Virens in the Biocontrol of Cotton Seedling Diseases

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract
Publication Acceptance Date: January 17, 2005
Publication Date: April 15, 2005
Citation: Howell, C.R., Puckhaber, L.S. 2005. Comparative biocontrol efficacies of "P" and "Q" strains of Trichoderma virens in the biocontrol of cotton seedling diseases [abstract]. Proceedings of Beltwide Cotton Conferences. p. 136.

Technical Abstract: Cotton seedling disease incited by pre-emergence damping-off pathogens can be effectively controlled by coating the seed with biocontrol preparations containing strains of Trichoderma species. However, the biocontrol treatments are much less effective in the control of post-emergence damping-off, since they do not colonize the plant hypocotyl and induce phytoalexin synthesis in that region of the plant. The post-emergence phase of cotton seedling disease can be controlled with systemic fungicides. However, these fungicides are not effective in controlling the pre-emergence phase of damping-off. In soil containing both pre and post-emergence pathogens neither the fungicides nor the biocontrol agents alone will control seedling disease. In an effort to control both phases of cotton seedling disease simultaneously, a series of chemical/biological combinations were used as seed treatments to determine which combinations would produce optimum disease control in soil infested with both pre and post-emergence pathogens. Tests showed that disease control was dependent on the fungicide, the cotton cultivar, and the biocontrol strain used. The optimum combination appeared to be chloroneb + the T. koningii x T. virens hybrid TKG-12, although other fungicide strain combinations were nearly as effective.