الفهرس 
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Abstract
ABSTRACT
Sayed Hassan Ahmed Agag:Pathogenic Variation in Ustilago scitaminae Causing Sugarcane Whip Smut in Egypt. M.Sc. Thesis, Plant Pathology Department, Faculty of Agriculture, Ain Shams University, 2015.
Sugarcane smut caused by Ustilago scitaminea Sydow occurs world wide and also in Egypt , causing serious losses in yield and also appears to reduce sugar quality . The morphological characteristics and molecular variation among four isolates of the pathogen collected from Minya ,Sohag,Qena and Luxor governorates in upper Egypt were studied. These isolates were differed in their pathogenicty on sugar cane plants. Disease survey was estimated during crop seasons of 2010 to 2012 in Minya , Sohag , Qena and Luxor governorates .The disease incidence was reduced in crop during 2012 season compared to 2010 and 2011. Teliospores from different governorates (Minya , Sohag , Qena and Luxor ) were morphologically similar when observed under light microscopy. They were light brown in color , double walled and also they were similar when they were examined using scanning electron microscopy. They were globose in shape , concave on one side with ornamental pattern on the outer surface. Growth pattern of the four isolates of Ustilago scitaminea on four different agar media (PDA,YGC,Malt extract and Suagrcane juice agar) was the same on each medium . The most aggressive isolate was that obtained from Luxor followed by Minya followed by Qena followed by Sohag in descending order when they were tested on commercial variety GT54-C9. The causal organism can be identify using specific primer , the target band had459kb long. It could be differentiate between the four isolates by six random primers using RAPD which clustered the four isolates into three groups , group one (Qena and Luxor isolates ) group two (Sohag isolate ) and group three (Minya isolate). Four fungicides (Preserve 6% FS, Premis 2.5% FS , Nine-ok 25% EC and Vitavax 40%FS) were used to study their effect on fungal growth and teliospore germination, all of them reduced the germination of teliospores at 5 ppm and also inhibit the radial growth of mycelium, two fungicides Premis 2.5% FS and Vitavax 40%FS were effectively
controlled the disease under green house conditions