الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
Tomato (Lycopersicom esculentum Mill) is one of the most important vegetable crop in Arab Republic of Egypt. It is attacked by many soil borne diseases such as damping-off, root-rot and wilting caused by Rhizoctonia solani, Sclerotium rolfsii and Fusarium oxysporum f sp. lycopersici which attack the roots and stem base of tomato plants during all stages of growth causing a considerable reduction in both yield and its
components.
This work aimed to survey for damping-off, root rots and wilting diseases at five governorates and isolation of the responsible pathogens.
Also, studying some factors affecting damping-off, root rots and wilting diseases i.e. inoculum potential, host range and varietals reaction of tomato plants. This is beside the biochemical changes due to infection with Rhizoctonia solani, Sclerotium rolfsii and Fusarium oxysporum fsp lycopersi.
This research also included studying the effect of certain biocontrol agents (fungi and bacteria) and biofertilization on the incidence of root-rot and wilting diseases of tomato plants as well as tomato productivity.
The obtained results could be summarised as follows:
1-- Surveying of tomato plant diseases in the tested locations and fields during seasons 200 land 2002 showed that higher percentages of diseases occurred during 2001 than 2002 year.
2- Isolation and identification of fungi from tomato plants during 2001 and 2002 seasons revealed that significant variation in
Summary -148-
fungi frequencies was observed among the governorates surveyed. Rhizoctonia solani, Fusarium oxysporum and Sclerotium rolfsii were more frequently occurred strains during two successive seasons. Followed by Fusarium sp, Macophomina sp, Verticillum sp and Pythium sp which were infrequently isolated during two seasons of survey. Rhizoctonia solani and F. oxysporum fsp lycopersici were the most frequent in their numbers and frequency followed by Sclerotium rolfsii, while Pythium sp was the fewer one during the two seasons. In this respect, the frequency of Rhizoctonia solani, Fusarium oxysporum and Sclerotium rolfsii were higher in 2001 than in 2002 season.
3- F.oxysporum fsp lycopersici, Rhizoctonia solani and Sclerotium rolfsii differed in their pathogenicity against tomato plants (Strain B variety) under greenhouse conditions. Fourteen strains of F. oxysporum fsp lycopersici were significantly pathogenic in different degrees. Strain Sa-F2 (from Sakha) was more virulent, while strain To-F (from Toukh) was the lowest one.
Meanwhile, thirteen strains of Rhizoctonia solani were tested. Etay-El Baroud and Sakha strains were more virulent, while strain Ka-R (from Kaha) was the lowest one.
Also, pathogenicity test of six strains of Sclerotium rolfsii was investigated. Results showed that El-Nubaria and Kafr-El zayat strains were the more virulent. While strain Etay-El Baroud was the lowest one. Concerning the pathogenicity test on tomato transplants, F. oxysporum fsp lycopersici and Rhizoctonia solani caused the highest
infection in descending order of virulence. Meanwhile, Sclerotium rolfsii recorded moderately percentage of
infection.