| Abstract: |
VI-SummaryBacterial wilt caused largely by Ralstonia solanacearum, a soil borne bacterium. It is one of the most destructive bacterial plant diseases. It causes devastating losses in affected potatoes and tomatoes and affects crops of economic importance such as : Potato ( Solamum tuberosum, L ), could be considered one of the most important vegetable crops in Egypt, since, It cultivated for local consumption as well as for exportation mainly to European markets.Unfortunately, potatoes are infected by brown-rot disease which causes destructive losses to such crop.This present work was planned to study : the integrated management to brown-rot disease of potato plant .The main results could be summarized as follows :1- Survey studies showed that, the highest percentage of infection and disease incidence were observed on Belquas-district in El-Dakahlia governorate which recorded the highest percent of potato brown-rot infection.2- Naturally infected potato tubers and plants, were collected from El-Dakahlia and El-Sharkia governorates to diagnose the disease and identify the bacterial causal agent .3- Twenty isolates of R.solanacearum pathogen, were isolated from the potato tubers collected from the two governorates. Morphological, physiological and enternistic antibiotic resistant were studied to performe these isolates, which revealed that : they 4- Pathogenic capabilities of 13 pathogenic isolates to infect potato plant was carried out under glass house conditions for potato plant ( Cara. c.v ). Results revealed that, the isolate No1 was the strongest one which caused the highest percentage of in5- Host range experiment under glass house conditions revealed that, the susceptibility of tomato plant for infection by R.solanacearum was the highest one compared with other tested plants .6- Diamont cultivar was the most resistant while, Sponta and Cara cultivars were the most susceptible for infection by R.solanacearum .7- Antagonistic microorganismis ( Bacteria and Actinomycetes) and avirulent strain with its phage were isolated from rhizosphere of potato plants grown in naturally heavily infested fields. The pathogenicity of isolated microorganismis were tested.8- Twelve antagonistic isolates which isolated from the rhizosphere of healthy potato plants, were identified as Bacillus sp (from No. 1 to No. 10) and Streptomyces sp ( two isolates No. 11&12 ).9- Evaluation experiment, under lab. conditions showed that : Bacillus sp isolate No. (1), streptomyces sp No.(11) were the most effective isolates where these isolates showed clear antagonism against the causal pathogen under test.10- Also this experiment showed that, thyme oil was the most effective material against R.solanacearum followed by peppermint, in contact or fumigation techniques. Clove, fennel and citronella oils exhibited completely and moderately inhibition the growth11- The effect of different plant extracts on the growth R.solanacearum was studied. The results showed that garlic cloves extract was the most effective one followed by Onion bulb extract and Jasmene leaves extracts exhibited the lowest inhibitory effect12- This work was extend to study the effect of treatments under green-house conditions where, avirulent strain with its phage was the best bioagent was used followed by Streptomyes sp (A1) isolate (11), which followed by avirulent strain, which finally f13- Under glass house conditions, Peppermint oil prevent germination of potato tubers, through fumigation technique, while, Thyme, Fennel and Clove oils had no effect on the germination of potato tubers.14- Under glass house conditions, the best disease control was obtained when added the plant extract ( Garlic cloves extract ), before the pathogen.15- Under field conditions, different bioagents, showed different degrees of efficacy against R.solanacearum where, avirulent strain and its phage was the best bioagent was used, since, the highest potato yield was obtained, followed by Streptomyces sp (AVI-SummaryBacterial wilt caused largely by Ralstonia solanacearum, a soil borne bacterium. It is one of the most destructive bacterial plant diseases. It causes devastating losses in affected potatoes and tomatoes and affects crops of economic importance such as : Potato ( Solamum tuberosum, L ), could be considered one of the most important vegetable crops in Egypt, since, It cultivated for local consumption as well as for exportation mainly to European markets.Unfortunately, potatoes are infected by brown-rot disease which causes destructive losses to such crop.This present work was planned to study : the integrated management to brown-rot disease of potato plant .The main results could be summarized as follows :1- Survey studies showed that, the highest percentage of infection and disease incidence were observed on Belquas-district in El-Dakahlia governorate which recorded the highest percent of potato brown-rot infection.2- Naturally infected potato tubers and plants, were collected from El-Dakahlia and El-Sharkia governorates to diagnose the disease and identify the bacterial causal agent .3- Twenty isolates of R.solanacearum pathogen, were isolated from the potato tubers collected from the two governorates. Morphological, physiological and enternistic antibiotic resistant were studied to performe these isolates, which revealed that : they 4- Pathogenic capabilities of 13 pathogenic isolates to infect potato plant was carried out under glass house conditions for potato plant ( Cara. c.v ). Results revealed that, the isolate No1 was the strongest one which caused the highest percentage of in5- Host range experiment under glass house conditions revealed that, the susceptibility of tomato plant for infection by R.solanacearum was the highest one compared with other tested plants .6- Diamont cultivar was the most resistant while, Sponta and Cara cultivars were the most susceptible for infection by R.solanacearum .7- Antagonistic microorganismis ( Bacteria and Actinomycetes) and avirulent strain with its phage were isolated from rhizosphere of potato plants grown in naturally heavily infested fields. The pathogenicity of isolated microorganismis were tested.8- Twelve antagonistic isolates which isolated from the rhizosphere of healthy potato plants, were identified as Bacillus sp (from No. 1 to No. 10) and Streptomyces sp ( two isolates No. 11&12 ).9- Evaluation experiment, under lab. conditions showed that : Bacillus sp isolate No. (1), streptomyces sp No.(11) were the most effective isolates where these isolates showed clear antagonism against the causal pathogen under test.10- Also this experiment showed that, thyme oil was the most effective material against R.solanacearum followed by peppermint, in contact or fumigation techniques. Clove, fennel and citronella oils exhibited completely and moderately inhibition the growth11- The effect of different plant extracts on the growth R.solanacearum was studied. The results showed that garlic cloves extract was the most effective one followed by Onion bulb extract and Jasmene leaves extracts exhibited the lowest inhibitory effect12- This work was extend to study the effect of treatments under green-house conditions where, avirulent strain with its phage was the best bioagent was used followed by Streptomyes sp (A1) isolate (11), which followed by avirulent strain, which finally f13- Under glass house conditions, Peppermint oil prevent germination of potato tubers, through fumigation technique, while, Thyme, Fennel and Clove oils had no effect on the germination of potato tubers.14- Under glass house conditions, the best disease control was obtained when added the plant extract ( Garlic cloves extract ), before the pathogen.15- Under field conditions, different bioagents, showed different degrees of efficacy against R.solanacearum where, avirulent strain and its phage was the best bioagent was used, since, the highest potato yield was obtained, followed by Streptomyces sp (AThe lowest effect obtained when clove and thyme oils were used as bioagents, the effects were cleared in healthy survival plants, regarding yield and disease-severity
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