الفهرس 
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Abstract
Sixteen isolates of Phialophora gregata from soybean stems were collected from six different geographic areas in Egypt (Beheira, Gharbia, Sharkia, Giza, Beni-Suif and El-Menia). Isolates were divided into two groups when grown on acidified potato dextrose agar (APDA) medium at 28°C by using morphology and cultural characteristic. Two specific primers flanking variable region were developed for easy identification of the genotypes using polymerase chain reaction (PCR).The two PCR products were used to separate isolates of P. gregata into distinct genotypes A (925 bp) and genotypes B (867 bp).The results of this study show that genotype A causes both leaf symptoms (a sudden interveinal chlorosis , necrosis and wilting of the leaves) and internal stem discoloration symptoms, while genotype B typically causes internal stem discoloration symptoms only. Cultivars Giza-82 and Giza-83 were resistant which gave the lowest percentage of internal stem discoloration percentage (PISD) followed by Giza-111 and Giza-21, while cultivars Crawford and Clark were susceptible which gave the highest percentage of PISD, while cultivars Giza-35 and Giza-22 were moderate resistant. Application of chemical inducers ( EDTA, SA, k2HPO4 and OA) under greenhouse and field conditions as seed soaking or foliar spray only or both seed soaking and foliar spray decreased brown stem rot disease (BSR) compared with the control and increased the activity level of peroxidase and polyphenoloxidase enzymes in infected plants, while catalase activity subjected to marked increase in healthy plants . Seed treatment with bioagents and biofungicides (T. harzianum, Biozeid, G. virens, Pseudomonas fluorescens, Bioarc and Pseudomonas putida) and fungicides (Topsin M-70,Rhizolex- T, Shirlan, Roveral and Sumisclex) decreased percentage of disease incidence compared with control under greenhouse and field conditions and increase in crop parametersbr>Key word : BSR, PISD, enzymes, activity, symptoms, seed soaking and foliar spray.