الفهرس 
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Abstract
The present study indicated that the fungus caused infection to bean, tomato and potato. The disease incidence and severity were 41.8 and 21.3, 48.7 and 22.4 and 59.0 41.0% in bean, tomato and potato, respectively. Out of 6 isolates derivative from bean, isolate SrB2 was the most virulent one. It causes DI and DS 45.0 and 31.1% respectively. While SrB1 isolate was the weakest one. It causes 21.3 DI and 16.6% DS. Isolate SrT4 was has highest virulence among Tomato isolates and the lowest one was SrT1. The disease incidence was 52.9 and 30.6 % and DS was 32.3 and 12.2% respectively. The most virulent isolate derivative from potato was SrP5. It causes DI 40.1 and DS 25.1% and the lowest one wasSrP5 which causes DI 29.4 and DS 12.2%.
All the tested bean cultivars are susceptible to S. rolfsii infection. Disease incidence ranged from 40.6 to 54.9 and disease severity from 22.4 to 29.0%. The most resistant one is Nebraska. In tomato, disease incidence ranged from 20.1 to 50.9% and disease severity from 18.0 to 29.6% and the most resistant one is CLX37032. Different susceptibility was detected in tested potato cultivars. Disease incidence ranged from 34.3 to 48.4% and disease severity from 19.3 to 30.6% and the most resistant one is Cara.
The current work shows that environmental factors i.e. temperature, nutrients, and relative humidity has a pronounced effect on growth of S. rolfsii. The highest linear growth was obtained in temperature of 25-30ᵒC. It was 71.2 and 78.4 mm. No deference was found between the linear growths of the tested isolates. Also the highest mycelial dry weight was detected in the same temperatures. It was 610 and 720 mg, respectively. Among the tested isolate,Srp5 had the highest dry weight and highest number of sclerotia formation was found in temperature of 25-30 C. it was 320 mg and 197 at25 C and 430 mg with 211.3 sclerotia at 30C.
As well as found the potato dextrose agar (PDA) medium and peptone sucrose agar (PSA) medium were suitable for the sclerotial production of the S. rolfsii. It was able to grow, germinate sclerotial and produce sclerotial with wide range of pH level. S. rolfsii showed rapid mycelial growth at 30°C which was significantly superior over the other temperature treatments. Neither growth nor sclerotial formation was recorded at minimum and maximum temperatures of 10 and 40°C. The optimum temperature for the better radial growth of the fungus ranged between 25 to 3o°C, whereas, for sclerotial production, it ranged from 20 to 30°C. The highest intensity of sclerotial observed at 30°C.
The obtained data show that adding neem oil to PDA at concentration of 2.0% caused inhibition in linear growth of the pathogen. The linear growth decreased from 90 mm in control treatment to 49 mm (inhibition 45.6). Mycelial linear growth was 66 and 72 mm as a result of adding garlic or onion extracts to media respectevily (inhibition was 26.7 and 20.0%). In the antagonism experiments, most inhibitory effect was noticed by B subtilus (linear growth 21 mm and about 76.7% inhibition) followed by P. fluorescens (41 mm and 45.5% inhibition).
The inhibitory effect of some antioxidants and hydrogen peroxide increased with increasing concentrations. The highest inhibitory effect was detected as a result of treatments with salicylic acid. The mean of linear growth was 35 mm compared with 85mm in control and the reduction in linear growth 60.6%. This effect was followed by hydrogen peroxide (47.0 mm and the reduction was 47.9%). In general, soaking of tomato seedling in antioxidants is more effective to reduce the disease occurrence than soil drenching. The most effective treatment was H2O2.The DI was 79.7 and DS was 19.3 % followed by SA that reduces DI 62.8 and DS 16.8 % compared to DI 100 and DS 39.2 % in control. Onion extracts have no potential to control S. rolfsii the most effective substance was neem oil which reduce DI and Ds to 44.4 and 8.13% respectively. On the other hands, the tested bioagents had a different potential to control the disease. The bioagent P. fluorescens recorded the best value on reducing DI and DS (44.4 and 10.4, respectively) followed by B. subtilis which caused DI 55.8 and DS 13.0. In all cases, fungicide Rhizolex had the highest control effect than all tested chemical substances, plant extracts and bioagents.