Damping-off and root rot/wilt diseases caused by the soil-borne fungi Fusarium solani and F. oxysporum are a serious problem of dry bean productions in Egypt. This study examines the potential of controlling these diseases biologically by using three Trichoderma isolates, compatible with the fungicide thiophanatemethyl, i.e., T. harzianum, T. viride, and T. virens. Soil application with inoculants containing these isolates employed either alone or in combination with seed coating with thiophanate-methyl was applied. Under greenhouse and field conditions, all treatments significantly reduced the incidence of damping-off and root rot/wilt diseases and increased the percentage of survival plants. These treatments increased vegetative growth parameters and yield components of the survival dry bean plants compared with untreated control. Soil application with Trichoderma isolates combined with thiophanate-methyl seed treatments was more effective than using both of them individually. Meanwhile, T. virens + thiophanate-methyl was the most effective treatment. The tested treatments stimulated systemic defense responses in dry bean plants by activating defense enzymes including peroxidase, polyphenoloxidase, and chitinase. Based on the obtained results, compatible isolates of Trichoderma spp. as soil treatment combined with thiophanate-methyl as seed treatment may have potential to develop a new biofungicide for integrated management of damping-off and root rot/wilt diseases in dry bean.

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.

Late wilt is a soil-borne disease caused by Cephalosporium maydis that severely limits maize production. In this study, endophytic Chaetomium isolates were screened for their abilities to control C. maydis on agar plates. In a dual culture test, Chaetomium spp. isolate Ch-1 inhibited 91.0% mycelial growth of C. maydis. The pathogen’s mycelial growth and conidial germination were also inhibited by its crude extracts. This isolate was identified as C. globosum (Chg-1) based on sequencing of the internal transcribed spacer regions of the rRNA gene. There are three Chg-1 application methods viz. grain treatment GT, soil application SA either individually or in combination GT + SA and two maize cultivars viz. landraces and fine seed 1005 were applied in pots and field plot experiments in controlling late wilt disease. In pots, Chg-1 treatments significantly reduced late wilt disease incidence and increased plant growth of the two maize cultivars, with a high efficacy for GT + SA compared to the positive control. Despite minor differences, treatments GT and SA provided adequate protection against late wilt. After 90 days of cultivation, the endophyte Chg-1 was re-isolated from the internodes of treated maize plants without causing any symptoms. This endophytic fungus reduced late wilt incidence in pots not only directly by antagonizing the pathogen, but also indirectly by inducing resistance mechanisms in maize plants. The induction of antioxidant enzymes (including peroxidase and polyphenoloxidase), chitinase, chlorophyll content, total phenols, and flavonoids was responsible for the indirect effects of Chg-1 against the pathogen. In the field, the endophyte not only reduced late wilt symptoms but also increased ear yield on both maize cultivars when compared to the untreated control. A combination of soil application and grain treatment with Chg-1 (GT + SA) outperformed any of these treatments individually in terms of reducing late wilt incidence and increasing grain yield in maize.