Potential of biocontrol agents against Ganoderma lucidum causing basal stem rot in mesquite (Prosopis cineraria) in arid regions of India

Abstract

This study investigates the potential of native biocontrol agents (BCAs) as controls against Ganoderma lucidum causing root rot mortality in Indian mesquite. The disease is prevalent in sandy soils where trees grow under rainfed conditions. In addition, a beetle namely Acanthophorus serraticornis damages the roots, resulting in increasing vulnerability of the host thereby allowing easy of the pathogen. In dual culture tests, Ganoderma infected cowpea root bit experiment and compatibility with insecticides revealed that the three BCAs (Trichoderma longibrachiatum, T. harzianum, and Aspergillus nidulans) significantly inhibited G. lucidum mycelial growth. The highest mycelial growth inhibition (47.6%) was recorded after 96 h followed by 39.8% and 29.3% at 72 and 48 h, respectively, by T. longibrachium. Cell free filtrates of T. longibrachiatum, T. harzianum, and A. nidulans were superior in inhibiting mycelium growth. A low concentration (3 ml) of T. longibrachiatum was more effective in inhibiting mycelium growth compared to other BCAs. Both Prosopis juliflora compost and onion residue compost amendments as food substrates favored the growth of these BCAs, which ultimately reduced the viability of Ganoderma-colonized root bits of cowpea. Studies on compatibility between insecticides and BCAs suggests that T. longibrachiatum, harzianum and A. nidulans can be combined with phorate or chloropyriphos (both organophosphates) at variable concentrations if amended together for partially infected trees, or as a prophylactic measure in healthy trees. These studies demonstrate that there is considerable opportunity for using native BCAs against G. lucidum in managing root rot disease.