الفهرس 
INTODUCTIONOnly 14 pages are availabe for public view
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Abstract
Tomato seedlings and plants showing typical root rot disease symptoms were collected from six locations (districts) in Minufiya governorate , i.e. Shebin El-kom ,Berkat Elsabie ,Al Sadat , Quiesna ,Tala and Ashmoon , representing different soil types and growing areas of tomato plants. These samples were used for isolation of fungi associated with diseased tomato plant materials. Isolation and purification of the causal organisms from the diseased materials was done and the results could be summarized as follows : 1- The isolated fungi were identified as F. solani , R. solani, Alternaria solani, Fusarium oxysporum and Trichoderma spp and other associated fungi were isolated with different values in frequency according to location of the diseased materials. 2-Fusarium solani was the most frequent fungus followed by Rhizoctonia solani and Alternaria solani. Other fungi were isolated from the same materials with low frequent. 3-associated fungi were purified and identified to determine their frequency distribution according to the location. SUMMARY - 110 - El-Sadat district oxhibited the highest frequency of in Fusarium solani percentage , followed by Queisna and Shebin El-kom district. 4-The total number of F. solani isolates from six districts of Minufiya governorate reached 16 isolates with 29.09 % frequency. Rhizoctonia solani was isolated from all tomato infected materials that collected from the six districts of Minufiya governorate, and 18.18 % frequency (10 isolates). Alternaria solani was isolated (5 isolates) by 9.09 % and came at the third rank of isolation within the total number of isolates. 5-Fifty five fungal isolates in pure cultures were isolated from tomato materials collected from different tomato growing areas in Minfiya governorate. F. solani was the most frequent fungus in El-Sadat ,Shebin El-Kom and Quisna , whereas R. solani was the most frequent in Shebin El-kom , El-Sadat and Ashmoon. 6-Ten fungal isolates were selected out of 55 fungal isolates from Minufiya governorate for pathogenicity tests according to their frequency, i.e. F. solani (5 isolates) , R. solani (3 isolates) and A. solani (2 isolates) to determine their virulence against five tomato genotypes , i.e. Nemastand , Dussehra , Ps 550, F1 743and SUMMARY - 111 - Hageen nour ; to define the most aggressive fungus and the most resistant and suitable genotype for economic production. 7- Pre-and Post- emergence damping-off percentages of tomato plants c.v. Nemastand were varied among F. solani five tested isolates as compared to control. Isolate 5 recorded the highest pre-emergence , whereas isolate 1 recorded the highest level of post-emergence damping –off. Survived plants recorded the least numbers of due to infection isolates 4&5 on the same genotype. 8-The highest percentage of pre-emergence was noticed in tomato plants c.v. Nemastand that inoculated with Rhizoctonia solani isolate 2, while the highest post-emergence was recorded in tomato plants inoculated with R. solani isolate 3. The highest number of survived plants was defermined in plants infected with R. solani isolate 1, while the least survivals were recorded in the case of isolate 2. 9-With regard to Alternaria solani (two isolates), pre-emergence damping-off on tomato seedlings was 70 % by both isolates, while post-emergence was 0.0 %. Survived plants recorded 30% (15 plants) in the case of A. solani tested isolates. 10- from all the obtained results, tomato genotype Ps 550 was the highly susceptible genotype, while tomato genotype F1 743 was SUMMARY - 112 - considered as the most tolerant genotype against damping –off diseases. 11- Trichoderma viride, Trichoderma harzianum, Bacillus subtilis, Pseudomonas spp.1 and Pseudomonas spp.2 were tested as biological control agents against the most pathogenic isolates, i.e. Fusarium solani isolate 5, Rhizoctonia solani isolate 3 and Alternaria solani isolate 2 that were selected as the most aggressive isolates. 12- The biological control agents affected the virulence of Fusarium solani. Trichoderma viride recorded 0.0 % pre-emergence of tolerant tomato genotype F1 743. The same percentage (0.0 %) was recorded also by T. viride in post – emergence dampingoff. The highest percentage survived plants was recorded by T. viride also on the same tomato genotype (100 %). 13- In case of Fusarium solani on the susceptible tomato genotype (Ps 550), Pseudomonas spp 1 recorded the lowest percentage of pre-emergence damping-off (10 %), while Pseudomonas spp 2 recorded the least post-emergence damping-off (6%). The highest percentage of survival plants was recorded in the case of Pseudomonas spp 2 (84 %). SUMMARY - 113 - 14- All tested bioagents greatly affected the disease incidence both on the tolerant and/or the susceptible tomato genotypes with variations in their responces against Rhizoctonia solani and Alternaria solani isolates. 15-Five fungicides were tested to control the disease incidence caused by the same three tested isolates of the three pathogenic fungi.These fungicides were Plant guard , Pink-hymexzole , Roforol 50 % , Thiophante and Rhizomak. 16-In most cases, the five tested fungicides were able to control seedling damping-off diseases on the tolerant tomato F1 743 incited by Fusarium solani. Plant guard recorded the least preemergence and post- emergence damping –off (0.0 %), as well caused the highest number of survived plants (100 %). 17- On susceptible tomato genotype (Ps 550), .The most effective fungicide against F. solani was Rhizomak in pre- and postemergence damping – off (0.0 %), as well as it showed the higest survived plants (100 %). 18- Plant guard and Thiophante greatly affected the incidence of pre – emergence damping off, they recorded (0.0 %), while Rhizomak recorded (0.0 %) in post- emergence damping off. The plant survivals recorded (96 %) by Rhizomak on the SUMMARY - 114 - susceptible tomato genotype (Ps 550) incited by Rhizoctonia solani. 19- The plants of both tolerant and /or susceptible genotypes infected with isolate of Alternaria solani treated by the five tested fungicides.