Suppressive Effect of Different Compost Extracts Against Fusarium oxysporum f. sp. ciceri: Causal Agent of Fusarium Wilt of Chickpea (Cicer arietinum)

Fusarium oxysporum f. sp. ciceri (Foc) is the causal agent of fusarium wilt in chickpea (Cicer arietinum). One of the main objectives of waste composting and management is to make available products that could contribute to soil health by fertilization and by suppressing plant pathogens. In this work, the suppressive effects of six different compost extracts A, B, C, D, E, and F at four different concentrations (extracts and their dilutions at 25%, 50%, and 75%) used either directly or after sterilization or not against Foc growth and sporulation were investigated. The composts were prepared mainly from tomato leaves in mixtures with other components at different ratios (sawdust, poultry manure, sheep manure, and olive pomace). All composts contain 50% tomato leaves and 20% sawdust but differ for other component contents. The results showed that all the compost extracts displayed an inhibitory effect on both Foc growth and sporulation by up to 89%. Following compost extracts sterilization, inhibition was reduced to only 53%. The inhibition of Foc growth varied according to the type of compost, the composting stage, and the compost extract concentration. The olive pomace free compost type A and type B, containing both sheep and poultry manure, were the most effective. This inhibition was mainly noticed at the second and fourth composting sampling stages corresponding to the 13th and 39th day after mixing the five components for composting. The suppressive effect of the compost type A and type B could be due to their manure content, which could be involved in the development of antagonistic microorganisms against the chickpea fusarium wilt agent.