Efficacy of Trichoderma asperellum against different pathogens of medicinal plants

Abstract

Trichoderma asperellum is one of the plant growth-promoting fungi (PGPF) presently marketed as biopesticide, biofertilizer and in soil amendments, due to its ability to protect plants, enhance vegetative growth and reduce pathogen populations. Keeping this in the view, here, we assessed its efficacy against pathogens of medicinal plants in vitro and in field conditions against the Leaf spot disease of Green leaf Tulsi (Ocimum basilicum). We selected 10 different plant pathogens of medicinal plants, namely Ashwagandha (Withania sominifera) pathogens (Alternaria alternata and Fusarium solani); Sarpgandha (Rauwolfia serpentina) pathogens (Colletotrichum sp. and Alternaria alternata); Tulsi (Ocimum basilicum) pathogens (Colletotrichum gloeosporioides and Alternaria alternata); Mint (Mentha arvensis) pathogens (Curvularia sp. and Alternaria alternata); and Mandukparni (Centella asiatica) pathogens (Cochliobolus sp. and Alternaria sp.) for evaluation by Dual culture plate method. After 144 h, maximum inhibition (56.36%) was recorded against F. solani. This was followed by inhibition of Cochliobolus sp. where the reduction was 55.38%. T. asperellum was also found to be effective against Alternaria sp. isolated from Ashwagandha (53.06%), Alternaria sp. from Sarpagandha (53.51%), and Curvularia sp. (52.12%). In field study, FYM enriched with T. asperellum, Pseudomonas fluorescence, neem oil and fungicide were tested against Leaf spot of Tulsi caused by Alternaria alternata. The treatment T5 [soil application of FYM (1.0 kg/m2) enriched with T. asperellum + P. fluorescence talc based formulation each @ 2.0% at planting time+ 3 sprays of copper oxychlorde @ 0.3% with 15 days interval on the onset of disease symptoms] was found effective with per cent disease index recorded 10.37%. This was followed by treatment T6 [soil application of FYM (1.0 kg/m2) enriched with T. asperellum + P. fluorescence talc based formulation each @ 2.0% at planting time + 3 sprays of with bordeaux mixture @ 0.5% onset of disease symptoms], and both the treatments were at par with each other. Maximum biomass of tulsi (3.97 g) observed in treatment T5. The result implies that FYM enriched with T. asperellum and P. fluorescence which was found to be most effective can be incorporated in IDM programs for ecofriendly leaf spot disease management of Green leaf Tulsi.