Integration of Trichoderma harzianum and natural plant products for the suppression of Fusarium wilt of tomato

Glasshouse studies were conducted to determine if disease suppression of Fusarium wilt of tomato could be enhanced by integrating Trichoderma harzianum with the bark of Khaya sp. (African mahogany) and leaves of Azadirachta indica (neem). Two Trichoderma harzianum isolates, from Greece (wild), and from a powder formulation from the Netherlands, were integrated with the botanicals by mixing spore suspensions of the isolates with extracts from Khaya sp. and A. indica, in various proportions. The mixtures were applied to two tomato accessions obtained from Ghana (GH4806 and GH5249) infected with Fusarium oxysporum f. sp. lycopersici, the disease-causing agent. Control of the disease was insufficient with T. harzianum and the plant extracts alone. Where the mixtures were applied, there was significant reduction in disease severity and the population of the disease-causing agent. There seemed to be stronger synergy between, the Greek isolate and Khaya sp. than Azadirachta indica. Disease reduction ranged between 63% and 100% for the mixtures. The two Trichoderma harzianum isolates reduced disease severity by 27.5% while Khaya sp. and Azadirachta indica reduced it by 46%. Integrating biologicals with natural products from plants has the potential to improve plant health, but need more studies to identify specific combinations for the management of plant diseases.