Antagonistic potential ofTrichoderma harzianumandAzadirachta indicaagainstFusarium oxysporumf. sp. capsicifor the management of chilli wilt

Fusarium oxysporumf. sp.capsici(Foc) induces wilt disease in chilli and affects its yield. Implementing microorganisms and plant extracts for plant disease management has recently gained momentum as chemical measures pose a serious threat to the environment. Field experiments were conducted over two consecutive years to evaluate the effectiveness ofTrichoderma harzianum(either as seed treatment or as soil application) and neem (Azadirachta indica; asseed treatment with leaf extract) alone or in combination, in managing chilli wilt. Untreated plots served as control. Chilli plants were grown in field plots of 2 x 2 m(2)size, and experiments were organised in complete randomised block design with three replications. In the absence ofFoc,T. harzianum(sa) + A. indica(st) increased growth and yield of chilli. InFoc-inoculated plots, both,T. harzianumandA. indica,showed a reduction in disease severity. Disease severity and chlorophyll content were negatively correlated (P <= 0.05). During both years,T.harzianum(sa) + A. indica(st) caused the strongest reduction in wilt severity and the highest increase in chlorophyll content, number of fruit/plant, fresh yield/plant, fresh and dry weight as well as plant length. Soil population ofT. harzianumincreased significantly during crop growth and was higher in plots inoculated with the pathogen. Highest concentrations (4.52 x 10(4)and 4.87 x 10(4) cfu/g soil) were found in plot soil whereT. harzianumwas applied in the soil, whilst maximum increase ofFoc(3.02 x 10(4)and 3.05 x 10(4) cfu/g soil) was observed in plots that lacked any treatment.

Automated summary

The use of Trichoderma harzianum and neem, either alone or in combination, can effectively reduce the severity of chilli wilt disease, leading to increased plant growth and yield.