Abstract
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 °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.
Highlights
Maize, Zea mays L., is one of the most important cereal crops worldwide
Little information has been cited in the literature on the efficiency of Trichoderma spp. against late wilt disease
The most abundant sugars are galactose, mannose, rhamnose, and glucose that reached more than 10% of total carbohydrates
Summary
Zea mays L., is one of the most important cereal crops worldwide. In Egypt, the cultivated maize area reached about 88,000 ha that yielded almost 7.2 million metric tons of grains (Anonymous 2017). Black bundle disease or late wilt, caused by Cephalosporium maydis, is one of the main economical and distributed maize diseases in Egypt (Samra et al 1963). Trichoderma spp. isolated from Egyptian soil were used as a biocontrol for Colletotrichum dracaenophilum and Fusarium proliferatum, based on results of laboratory trials (Morsy and Elshahawy 2016 and Elshahawy et al 2017a). It reduced disease caused by the soil-borne fungus Stromatinia cepivora (Berk.) and induced plant resistance in onion plants when applied to soil (Elshahawy et al 2017b)
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