الفهرس 
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Abstract
The obtained results of the present study could be summarized as follows:
-Different sources of potato brown rot bacteria,ralstonia
solanacearum, are recognized such as potato tuber tissues, soil, irrigation water and some aquatic plants In Menufiya the most frequency of R. solanacearum was pronounced in either potato tuber tissues ( 40% frequency) or in soil (15.3 % )
followed by Minia region (33% in potato tuber tissues and 6.1 % in
soil).
Under Nubaria conditions, the least frequency of R. solanacearum was
reported (30% in potato tuber tissues and 4.6% in soil)
Survey of R. solanacearum in soil showed lack of the culturable level
of the R. solanacearum during June to August 1999.
New potential hosts i.e. Amaranthus sylvesteris and Eichornia cassipes
for R. solanacearum are recorded.
Irrigation water plays a major role for dissemination of R.
solanacearum from roots of aquatic plant hosts to fields.
Each detection method used for detecting R. solanacearum had
advantages and disadvantages.
Indicator plants such as tomato, banana, and tobacco plus the ability of
bacteria to utilize hexose alcohols or disaccharides still the most
accuracy detection methods of R. solanacearum races and biovars.