الفهرس 
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Abstract
Late wilt disease caused by Cephalosporium maydis is still one of the most serious diseases of maize in Egypt. Ten isolates of C. maydis were isolated from samples of maize plants showing late wilt disease symptoms, collected from 10 governorates in Egypt and they were evaluated under greenhouse conditions for virulence on two maize cultivars Sc, 10(resistant) and Baladi cultivar (susceptible). C. maydis No. 3 was the most aggressive one. Sucrose –yeast medium was the most suitable for maximization the growth of C. maydis. The optimum temperature for growth of all isolates was 30 ºC followed by 25 ºC. Out of eleven fungal species only three species identified as Aspergillus flavus, Fusarium oxysporum and Penicillium citrinum were found to produce extracellular silver nanoparticles .It was found that nanosilver extracted from A. flavus, F. oxysporum and P. citrinum have different shapes (spherical and triangular) and diameter size (9-50nm).These nanoparticles exhibited inhibitory effect on C.maydis growth on culture media and this effect varied according to the size of particles .The results of this study showed that nanosilver decreases the disease incidence in maize plant especially that synthesized by F. oxysporum marked increases in stem elongation was found in case of infected plants injected with silver nanoparticles specially those produced by A. flavus .Also there were increasing in plant hormones in infected plants which were injected with nanosilver specially those of A. flavus .It is of conceivable to speculate that there are correlation between the presence of nanoparticles with stem elongation, plant hormones and disease incidence in maize plant .It could be concluded that AgNps was effective in the disease control caused by C. maydis. C. maydis was found to produce 7-amonocephlosporinic acid that determined by GC-MS.