Maximizing the efficacy of Trichoderma to control Cephalosporium maydis, causing maize late wilt disease, using freshwater microalgae extracts

The main goal of this study was enhancing the biocontrol activity of Trichoderma spp. (T. harzianum, T. koningii, T. viride, and T. virens) against Cephalosporium maydis, the cause of late wilt disease in maize. Five isolates of C. maydis were isolated from diseased maize plants, showing late wilt symptoms, and were collected from infected maize fields in Gharbia Governorate, Egypt. Pathogenicity test revealed that all C. maydis isolates were able to attack maize plants (cv. Baladi), which cause late wilt disease. Isolate 3 (Cm3) was the most virulent of them. In in vitro experiments, vegetative growth of the mycelium of C. maydis was highly inhibited after opposite sides' treatment by Trichoderma species on Potato Dextrose Agar plates amended with Chlorella vulgaris extracts (cool and hot extracts) than unamended one. Formulation of C. vulgaris extracts and Trichoderma spp. were prepared. The formulations maintained the capacity of Trichoderma spp. to inhibit growth of the pathogen for up to 1 year when stored at both room temperature or at 7 degrees C. These formulations (3-day-old) were examined for biological control activities against late wilt disease of maize. Under greenhouse and field conditions, all treatments reduced late wilt incidence compared to the untreated control. Treatments involved Trichoderma spp., and C. vulgaris extracts were more effective than that used individually. Both of the C. vulgaris extracts, with each of T. virens and T. koningii, were the most effective treatments in this respect. Under greenhouse conditions, formulation treatments (C. vulgaris extracts and Trichoderma spp.) significantly increase the plant growth of maize plants, i.e., plant height and plant dry weight as compared to the non-treated control either in infested or in un-infested soil with C. maydis. Under field conditions, these formulations increased the grain yield as well as ear parameters as compared with either C. vulgaris extracts or Trichoderma spp. alone as well as non-treated control. This study suggests that the efficacy of Trichoderma spp. was enhanced with C. vulgaris extracts and these formulations can be developed as bio-fungicides for minimizing the late wilt disease caused by C. maydis in maize.