Eight isolates of Fusarium oxysporum f.sp. cucumerinum; the causal organism of Fusarium wilt of cucumber plants; were isolated from wilted cucumber plant samples collected from eight different localities in Egypt . These isolates were pathogenic to the susceptible cucumber cultivar "Biet alpha". Isolate 3 was the most virulent, followed by isolate 4 , while the least pathogenic was isolate 5. Potato Dextrose medium was the best medium for linear and amount of growth for all tested isolates, whereas rate of growth varied between the different tested isolates with the different tested media. Optimum temperature for the fungal linear growth was 27°C, followed by 28°C, while the best amount of growth was obtained at 25°C for all tested isolates. Cucumber genotypes were susceptible to Fusarium oxysporum f.sp. cucumerinum and differed significantly in their susceptibility. The most tolerant cucumber genotype was "Zeina" as well as it recorded the highest survival plants. DNA analysis detected 33 loci with an average 4.125 loci/isolate. The highest number of polymorphic loci was 6 loci in both Fus 1&4 isolates, while the lowest was 1 loci in Fus 6 only. UPGMA cluster analysis divide into two sub clusters, one of them included Fus 6 only and the second include the rest seven isolates with different similarity values. 100 & 614 bp were detected in both highly pathogenic isolates and it could be carrying the genetic information affecting pathogenicity of Fusarium to cucumber plants. Grouping of Trichoderma isolates in UPGMA cluster analysis and variation in DNA profiles among isolates was not related to their biocontrol ability. Biocontrol agents great affected Fusarium growth in dual cultures and reduced it under laboratory conditions. Biocontrol agents minimized the disease parameters in comparing with infested control treatments by the most aggressive isolate under greenhouse condition.

The efficiency of two bacterial strains, namely: Bacillus subtilis Bs2 and B. mycoides Bm7 that have been previously isolated from petroleum-polluted soil in Saudi Arabia, for bioremediation of hydrocarbons-polluted soil were studied. The results indicated that both bacterial strains played an influential role in elimination of the phytotoxicity of benzene and toluene as evidenced by the pronounced increments in percentages of grain germination and viability of emerged seedlings, chlorophylls and carotenoids pigments contents of leaves as well as the significant improvement in plant growth vigor (root length, plant height and biomass gain) of barley (Hordeum vulgare L.) "Madini" cultivar as compared to that cultivated in untreated hydrocarbonpolluted soil under the same environmental conditions. However, B. subtilis Bs2 proved by far to surpass B. mycoides Bm7 in its bioremediation potential.

Eleven isolates belonging to genus Trichoderma were isolated from the rhizosphere of watermelon roots grown at different localities in Egyptian soil. They were morphologically identified as T. harzianum, T. hamatum, T. glaucum, T. reesei and T. viride. These five species comprised different eleven isolates which were originated from different localities. significant differences in radial growth of the different pathogens tested. Also, there was a significant difference between the pathogens in dual culture and the control treatment which include the pathogen only. Results lead us to conclude that DNA based RAPD provide a reliable method for grouping isolates of Trichoderma spp. In addition, analyzing phyllogenetic similarities among isolates based on DNA pattern according to RAPD technique. Genomic DNA prepared from the eleven Trichoderma spp. isolates was used to screen primer for readily detectable and reproducible polymophic PCR amplifications. The PCR conditions employed, allowed amplification of many bands on the agarose gel. Bands present in each sample were scored for presence and absence of amplification products. UPGMA cluster analysis divided in two subclusters; the first one included the T. harazianum isolates. However, the second cluster included the T. hamatum and T. glaucum isolates. Meantime, each isolate of T. reesei and T. viride fall in one another subcluster showing the lowest similarity with other isolates. Results conclude that the differences in DNA profiles among isolates of Trichoderma species not related to their geographic origin or biocontrol ability. The biocontrol ability of the tested isolates of Trichoderma species under greenhouse condition, against the different pathogens using the susceptible watermelon cultivar Giza 1 were studied. Results obtained showed the effectiveness of all isolates of Trichoderma species in this respect. Results also showed the superiority of T. harzianum and T. hamatum isolates as well as T. reesei in some cases against the tested pathogens.

Root rot and vine decline (MRR/VD) disease of cucurbits caused by Monosporascus cannonballus is one of the recently described diseases in Egypt. The inciting is a soil borne fungus classified as Ascomycetes fungus named Monosporascus cannonballus Pollack and Uecker belonged to order Sordariales, family Sordariacea. Field and in vitro experiments examined the distribution and pathogenicity of M. cannonballus. The disease occurred in Egypt on cultivated cucurbits i.e. cantaloupe (Cucumis melo var. cantulepensis), watermelon (Citrullus lanatus) and cucumber (Cucumis sativus) plants. In three years of disease survey, the disease occurred at 10, 10 and 2 fields of cantaloupe, watermelon and cucumber, respectively during late summer of 2006, 2007 and 2008, which were located at Nubariya (Behaira), Sumosta (Beni Suif), Gamsa (Demietta), Kasassin and Tal El-Kaper (Ismailia), َQueisna and Sadat city (Minufiya), El-Arish (North Sinai), Salhiya and Abu Kabir (Sharkyia)Disease progression in different tested cucurbits grown in fields at different localities was not observed until the fruit set stage of plant growth, but rapidly increased at the fruit maturity stage (10 to 14 days pre-harvest) resulting yield loss reached more than 50%. The isolation rate of M. cannonballus reached 22.0% from diseased hosts. In in vitro test, diseased seedlings after one to two weeks of inoculation and perithecia were formed in infected roots 21 days later. Also all tested isolates were pathogenic to all tested cucurbit host plants.