Abstract

In this current study, the beneficial filamentous fungi, Trichoderma virens, isolated from cassava field were investigated for antagonistic mode of action against Lasiodiplodia theobromae, the causal agent of cassava stem rot in Thailand. In vitroscreening using the dual culture technique was undertaken to assess the potential of these Trichoderma isolates. Our results indicated that fifteen isolates of T. virenswere collected from various areas of cassava field in Nakhon Ratchasima, Thailand. The T. virens isolate, TvSUT10, was the most effective isolate and inhibited L. theobromae mycelial growth by 84.12%, due to the antagonistic mechanism. Moreover, Trichoderma β-1,3-glucanase activity was determined, the result revealed that the highest activity was recorded in strain of T. virens TvSUT10 (25.7 U/ml). In addition, in the greenhouse experiment, the application of the TvSUT10 as a conidial suspension reduced the stem rot disease severity of cassava caused by 53%. The results indicated that the T. virens strain TvSUT10 has initial modes of action of biological control to protect cassava crop against L. theobromae infections in cassava.

Key words: Trichoderma, cassava stem rot disease, growth inhibition, cassava, biocontrol.

Abbreviation

Abbreviations: PR, Pathogenesis-related; SA, salicylic acid; JA, Jasmonic acid;PDA, potato dextrose agar; MGI, mycelial growth inhibition; MSM, minimal synthetic medium.