ZnO-based nanomaterials have high antifungal effects, such as inhibition of growth and reproduction of some pathogenic fungi, such as Fusarium sp., Rhizoctonia solani and Macrophomina phaseolina. Therefore, we report the extracellular synthesis of ZnONPs using a potential fungal antagonist (Trichoderma harzianum). ZnONPs were then characterized for their size, shape, charge and composition by visual analysis, UV–visible spectrometry, X-ray diffraction (XRD), Zeta potential, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The TEM test confirmed that the size of the produced ZnONPs was 8–23 nm. The green synthesized ZnONPs were characterized by Fourier transform infrared spectroscopy (FTIR) studies to reveal the functional group attributed to the formation of ZnONPs. For the first time, trichogenic ZnONPs were shown to have fungicidal action against three soil–cotton pathogenic fungi in the laboratory and greenhouse. An antifungal examination was used to evaluate the bioactivity of the mycogenic ZnONPs in addition to two chemical fungicides (Moncut and Maxim XL) against three soil-borne pathogens, including Fusarium sp., Rhizoctonia solani and Macrophomina phaseolina. The findings of this study show a novel fungicidal activity in in vitro assay for complete inhibition of fungal growth of tested plant pathogenic fungi, as well as a considerable reduction in cotton seedling disease symptoms under greenhouse conditions. The formulation of a trichogenic ZnONPs form was found to increase its antifungal effect significantly. Finally, the utilization of biocontrol agents, such as T. harzianum, could be a safe strategy for the synthesis of a medium-scale of ZnONPs and employ it for fungal disease control in cotton.

even different fungi were isolated from the necrotic root tissues of infected Flax seedlings or older plants. Samples used in isolation were randomly collected from the experimental flax plots at Giza Agricultural Research Station. Fusarium spp. were isolated most frequently comprising 41.09%, while frequencies of isolation of the other fungi ranged from 1.00 to 23.97%. Regression analysis revealed that root colonization incidence (RCI) and root colonization severity (RCS) and relationship of rootcolonizating fungi of flax conformed to the linear model. According to the generated model, RCI accounted for 89.8% of the total variation in RCS. A total of 52 randomly selected isolates from infected roots were tested for pathogencity on flax cultivar Sakha 1 under greenhouse conditions. The results of pathogenicity test demonstrated that Fusarium spp. are the major causal agents of flax seedling blight as they accounted for 54% of the pathogenic isolates in the test. A total of 103 monosporic Fusarium isolates were randomly colleced from eight governorates and identified to species level. F.oxysporum (63.60%) and F.solani (27.35%) were the most predominant species. Other species were F.moniliforme (3.88%), F.lateritium(1.04%), F.semitectum (0.66%) and unidentified Fusarium spp. (3.49%). RCI and RCS relationship of rootcolonizing fusaria of flax conformed to the linear model. According to the generated model, RCI accounted for 75.3% of the total variation in RCS. Of the 103 isolates, a random sample of 32 isolates were tested for pthogenicity on seedlings of flax cultivar Giza 10 under greenhouse conditions. The results of the pathogenicity test showed that 66.67% of pathogenic isolates belonged to F.oxysporum, while 33.33% belonged to F.solani. The high frequencies F.oxysporum and F.solani and their ability to cause considerable losses during seedling stage, strongly suggest that they are the most important fusaria involved in the etiology of seedling blight and root rot of flax in Egypt. Grouping the isolates of F.oxysporum, F.solani, and F.lateritium by cluster analysis, based on their virulence patterns was neither related to their geographic origins nor to species.

Pathogenicity of eight Bacillus strains to seedlings of four cotton cultivars was evaluated under greenhouse conditions. Each of the tested cultivars was individually treated with powdered inoculum of each bacterial strain. Untreated seeds were planted as control treatments in autoclaved soil. Effects of the tested strains on levels and activities of some biochemical components of the infected seedlings were also assayed. The biochemical components included total soluble sugars, total soluble proteins, total free amino acids, peroxidase, polyphenol oxidase, phenols, and lipid peroxidation. ANOVA showed that Bacillus strain (B) was a very highly significant source of variation in damping-off and dry weight. Cotton cultivar (V) was a nonsignificant source of variation in damping-off while it was a significant source of variation in dry weight. B × V interaction was a significant source of variation in damping-off and a nonsignificant source of variation in dry weight. Bacillus strain was the most important source of variation as it accounted for 59.36 and 64.99% of the explained (model) variation in damping-off and dry weight, respectively. The lack of significant correlation between levels and activities of the assayed biochemical components and incidence of damping-off clearly demonstrated that these biochemical components were not involved in the pathogenicity of the tested strains. Therefore, it was hypothesized that the pathogenicity of the tested strains could be due to the effect of cell wall degrading enzymes of pathogenic toxins. Based on the results of the present study, Bacillus strains should be considered in studying the etiology of cotton seedling damping-off.

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Proteins of 15 isolates of T. longbrachiatum and T. harzianum were compared by polyacrylamid gel electrophoresis (PAGE) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Gels were stained with silver nitrate. Protein banding patterns of the isolates were subjected to cluster analysis by the unweighted pair-group method based on arithmetic mean (UPGMA).