The development of a model to predict the potential efficacy of Trichoderma harzianum isolates on perithecial production of Gibberella zeae based on secondary metabolite production

Fusarium head blight (FHB) is an important disease of wheat and causes significant economic and yield losses. The principal pathogen associated with FHB in Manitoba is Gibberella zeae (Schwein.) Petch (anamorph = Fusarium graminearum Schwabe). Trichoderma harzianum Rifai is a well-known biocontrol agent of many plant pathogens. The extracts from 11 T. harzianum isolates and cellfree filtrates were screened for antifungal activity against perithecial development. Isolates T472 and T22 (RootShieldTM positive control) significantly reduced perithecia numbers by more than 70%. It was found that isolates T472 and T22 had similar chemical composition. Through the use of cluster analysis, ordination and regression methods, several compounds (C18, C22, C27 and C42) were unique to T472 and T22 and may be responsible for the reduction in perithecia. A multivariate weighted average (WA) regression approach demonstrated that the use of chemical signatures is an effective method in predicting which isolates and compounds maybe be involved in reducing perithecial numbers. The R2 for the WA analysis was 0.745.