Compatibility of Trichoderma asperellum isolates to selected soil fungicides

Fungicides are used frequently to manage plant diseases effectively, but human health and environmental concerns often put pressure on growers to reduce the number of applications. One approach is to integrate biological control agents (BCA) with fungicide use. In order to be effective, it is important that the BCA is compatible with the desired fungicide. Trichoderma asperellum has been studied extensively as a BCA with results dependent upon the specificity of the isolate. In this study, 12 different T. asperellum isolates along with one T. koningiopsis isolate were studied for their response to soil fungicides. In a poison plate assay, there was a significant interaction between the isolate and fungicide at the recommended rate. No fungicides completely inhibited growth, but some did significantly suppress it. In addition, three isolates were selected to investigate survival of conidia in soil after application of selected fungicides. After 1 week exposure in soil, no fungicide completely killed conidia although some fungicides had a limited effect on survival. There did not appear to be a correlation between the poison plate assay results and conidia survival, emphasizing the importance of doing both tests.