Impact of Trichoderma-based products on Sclerotinia sclerotiorum1

ABSTRACT Trichoderma-based products are deployed on a large scale in regions where white mold is important. However, little is known about the contribution of alternating these products on sclerotia parasitism, disease incidence and plant yield. This study aimed to apply Trichoderma-based products sprayed alone or alternately, at the V2 and V4 phenological stages, in order to evaluate their effectiveness in controlling white mold in soybean. The treatments were: control (water); Trichoderma harzianum IBLF 006; T. harzianum BK-Th001; T. harzianum IBLF 006 followed by T. harzianum BK-Th001; and T. harzianum BK-Th001 followed by T. harzianum IBLF 006. Two field trials were conducted in different locations. Yield-related variables (thousand-grain weight and number of pods), grain yield, and white-mold-related variables (disease incidence; sclerotium parasitism, germination and viability; and number of apothecia) were evaluated on sclerotia originated from the field and produced in the laboratory. All the treatments with biocontrol agents reduced the incidence of white mold, when compared to the control, whereas the Trichoderma. spray reduced the sclerotium germination. The sclerotia origin (laboratory or field) affected their ability to produce apothecia and cause the disease. The application of these biological control agents, regardless of sequence, reduced the sclerotia viability and disease incidence, and improved the yield.