الفهرس 
Causal organismsOnly 14 pages are availabe for public view
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Abstract
The present study was carried out in order to select and increase the antimicrobial activity of some soil inicroorganisms to be wed io the biological control of leaf spot pathogens of sugar beet Cercosporn beticoln and Alternnrin nlteritatn. This was achieved through isola t ioil, screening and optimization of the nutritional and physical requirements ihr the most active microorganisms. The study began by isolating and puriling fourty-seven inicroorganisms including fiingi, bacteria and actinomycetes from Egyptian soils collected from fields cultivated with the sugar beet at Kaf? El-Sheikh Governorate. I Most of these isolates were found to have antagonistic activity against C. beticoln and A. nlterncrtn. Out of the Iburty-seven isolates, ninteen isolates have antagonistic activity against A. nlterircrtcr, and fourteen isolates against C. beticola. The four most active isolates against C, beticoln and A. nlterrtritrr were identified. The isolate No. 1 was identified as Streptorryces rrrrirlirtrrs (syn. S. cavoirrertsis), the isolate No. 3 was identified as Streptonzyces chromofilscrrs (syn. S. gnlbirs), the isolate No. 2 1 was identified as Streptomyces nlbntlrr~tcrrs and The isolate No. 3 5 was identified as T. viride. The effect of different conenkrations of the culture filtrate produced from the cult~ires of S. nrtirlntris, S. chromofilscus, S. nlbnclrrircirs and T. viricle were sttidied in vitro againstC. beticoln and A. nltreitnto in terms of growth (dry biomass), spore germination and sponilation.