Efficiency and delivery methods of Trichoderma harzianum on biological control against southern blight in sweet pepper

Abstract

Soilborne pathogens are difficult to control with limited options, and it is important to seek effective alternatives for management. The objective of this study was to evaluate the effect of Trichoderma harzianum on the biological control of southern blight. The commercial product Trichodermil, containing the antagonist, was used for in vitro antagonism evaluation, followed by in vivo assays, with different forms of biocontrol application in Capsicum annuum seedlings inoculated with Sclerotium rolfsii. The biocontrol conditions used in the tests were: 1) without inoculation of the pathogen; 2) furrow spraying; 3) foliar spraying; 4) immersion of roots in spore suspension; 5) without biocontrol. The T. harzianum isolate tested produces antifungal metabolites that reduce mycelial growth and germination of the pathogen. In the in vivo tests, an effect of the application in the sowing furrow on the root mass of the plants was observed. However, none of the treatments prevented plant mortality. The biocontrol agent T. harzianum does not work as a stand-alone strategy for management of southern blight, but has potential for use in integrated management programs.