Management of sunflower charcoal-rot and maize late-wilt diseases using the aqueous extract of vermicompost (vermitea) and environmental-safe biochar derivative (wood vinegar)

Abstract

In Egypt, sunflower charcoal-rot caused by Macrophomina phaseolina and maize late-wilt caused by Magnaporthiopsis maydis are the most prevalent, and can lead to huge yield losses of both crops under epidemic conditions. In this study, the potential use of vermitea and wood vinegar for management of both diseases was investigated. Data revealed that, among the 17 bacterial strains obtained from vermitea, three strains named VCB-2, VCB-7 and VCB-11 were chosen for having the greatest in vitro inhibitory effect against M. phaseolina and M. maydis, with fungal inhibition values of 54.2; 61.7, 65.2; 74.0 and 57.1; 87.0% against both pathogens, respectively. These strains were identified as Bacillus amyloliquefaciens, Serratia marcescens and Bacillus velezensis, respectively. Wood vinegar significantly reduced the colony diameter of M. phaseolina and M. maydis in in vitro trials conducted on potato dextrose agar medium amended with the desired concentrations of 0.5, 1.0, 1.5, 2.0, and 2.5%. The efficiency increased with increasing wood vinegar concentration, and 2.0% was the most effective (100% suppression). Data from greenhouse experiments showed that the application of vermitea or wood vinegar tended to decrease the incidence (% dead plants) of sunflower charcoal-rot (by 61.1 and 66.7%) and maize late-wilt (by 70.6%). These treatments had positive impacts on the plant growth parameters, photosynthetic pigments and antioxidative enzymes of sunflower and maize plants. Data from field experiments showed that the application of vermitea or wood vinegar decreased the incidence of charcoal-rot (by 72.8 and 72.0%) and late-wilt (by 88.7 and 87.0%) as well as increased the production sunflower and maize plants.