الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Alternaria black leaf spot disease is one of the most common and destructive diseases of cabbage, A. brassicicola has proven to be the main causative agent of Alternaria leaf spot of cabbage.
Screening of cabbage Alternaria leaf spot disease in different localities of El-Sharkia governorate was carried out during 2010-2011 growing season. Alternaria black leaf spot disease appeared to be wide spread in cabbage fields. Isolation procedures yielded several fungal genera with variable frequencies but A. brassicicola was the most frequently isolated fungus compared with others. Pathogenicity tests confirmed that A. brassicicola was the most pathogenic fungus either inoculated on detached (in vitro) or attached cabbage leaves (in vivo). Cultivar reaction test revealed that OS-Cross cv. was the most resistant cabbage cultivar while Balady cv. was the most susceptible one. Evaluation of the susceptibility of different hosts against Alternaria black leaf spot disease showed that only family brassicaceae plants were affected by Alternaria brassicicola but, no disease symptoms occurred on tested plants belonged to other families. Environmental studies proved that cabbage leaves extract and PDA media highly enhanced the linear growth and the sporulation of A.brassicicola at 250C under 12hrs light duration. Physiological studies indicated that the activity of peroxidase (PO) and polyphenol oxidase (PPO) increased by infection in all tested cultivars compared with healthy uninfected samples, total phenols concentration reduced by infection in most tested cultivars but, in some instances it has been shown to increase after infection. Ascorbic acid content got reduced by infection in all tested cultivars on the other hand, pH increased by infection in all tested cultivars. Biological control studies indicated that Trichoderma album was the most effective fungal bioagent decreasing A. brassicicola linear growth in vtiro using dual culture technique, whereas bacterial isolates (B1and Bacillus subtilis) as well as their culture filtrates proved to be the most effective in reducing Alternaria brassicicola spore germination and subsequently reducing the disease parameters when applied protectively on detached and\or attached leaves. Among tested plant extracts against A. brassicicola, only hot extraction of black nightshade revealed the best results concerning the linear growth in vitro using poisoned food technique media. Chemical control experiments indicated that score was highly effective in inhibiting A. brassicicola linear growth and sporulation consequently it gave the best results when applied as a curative treatment on detached and\or attached leaves, on the other hand, diathane-M45 proved to be the most effective in inhibiting spore germination or germ tube elongation of A.brassicicola, consequently it was the best tested fungicide reducing disease parameters when applied as protective treatment on detached and\or attached leaves.