In vitro evaluation of antagonism by Trichoderma spp. towards Phellinus noxius associated with rain tree (Samanea saman) and Senegal mahogany (Khaya senegalensis)

Abstract

A series of laboratory tests was conducted to screen and identify Tnchoderma spp. for the biological control of P. noxius on pruning wounds. In total, 7 Trichoderma isolates were evaluated for their biological fitness and antagonism towards 2 different P. noxius isolates associated with Senegal mahogany and rain tree in Singapore. The competitive ability of various Trichoderma isolates was assessed by their germination rates, growth rates, and chlamydospore production; and the antagonism of P. noxius by Trichoderma was assessed by the interaction of these fungi in dual culture and on wood blocks. In this study, the Trichoderma isolates showed greater competitiveness and antagonism towards P. noxius compared to similar reports in the literature. A majority of the Trichoderma isolates germinated and grew at consistently high rates, but there was considerable variability in the production of chlamydospores among isolates. All Trichoderma isolates routinely antagonized P. noxius in the different bioassays, but there was significant variability in the antagonistic capacity of various isolates and in the susceptibility of the P. noxius isolates to confrontation with Trichoderma. Relative to the controls, P. noxius cultures grew significantly slower in the presence of volatile organic compounds emitted by most Trichoderma isolates, and a large majority of Trichoderma isolates caused a significant reduction to the dry weight loss of wood blocks inoculated with P. noxius. Although no single Trichoderma isolate consistently antagonized P. noxius better than all others in every test, T. harzianum 9132 and T. virens W23 notably did so more regularly than others.