الفهرس 
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Abstract
The present study was carried out investigate the impact of different composts controlling on potato common scab disease under Minia governorate condition. Results of this work can be summeriged as follows:
1- In fall season, all potato cultivars appeared common scab symptoms. Both incidence (DI) and severity (DS) of common scab were significant varied with cultivars and locations. Highest number of scabbed tubers was reported by potato cv. Burna season in Damarees followed by Bokhara cv, in Damarees. Meanwhile, potato cultivars Cara showed least number of scabbed tubers (9% common scab incidence) in Zohra . As for potato common scab severity, potato cultivar Burna and Bokhara gave this highest value of that growing in Damarees. Least value of potato common scab severity was proved by cv. Lady Bedford in Zohra followed by Cara cv. In Damarees. In summer season potato common scab incidence highest value of was seemed by potato tubers of Berna cv. in Damarees followed by Lady Bedford (28 % DI) growing in Zohra . While Cara cv. And least number of scabbed tubers value in Damarees. The high least values of potato common scab severity was given by potato cv. Berna grow in Zohra and El-Borjaia , susceptibility potato Cara cv. Revealed least common scab severity in Zohra location followed by Lady Bedford cv. in Damarees .
2- Four pathogenic bacterial isolates were isolated and showed significant virulence values, since isolate CS1 was the most regressive isolate followed by CS2 and CS4. Isolate CS3 was the least pathogenic.
3 - Identification trial that based on the morphological, biochemical and physiological properties reviled that all 4 bacterial isolates were similarly reacted as Streptomyces scabies (Thaxter).
4 - Streptomyces scabies isolates were significantly in their pathogenicity to potato cultivars varied. Potato cultivar Berna gave the highest incidence and severity by isolate CS1. Potato cultivar Armada and Bukhara readout as intermediate. Least values of common scab incidence and severity were given by potato cv. Flora.
5 - Application of Nile compost or Al obour composts as soil amendment gave various effects towards potato common scab causal pathogen isolate CS1. In fall seasons of 2014 a significant difference recorded between concentrations of tested compost. Cutest significant potato common scab incidence and severity was expressed when potato plant cv. Berna grown in soil amendment by 2.5 Kg Nile compost /M2 soil. Al obour compost above lasses effective to reduce potato common scab as compared with Nile compost. However highest percentage of protection was explored in fall season of 2014 by soil amendment by 2.5Kg Nile compost/M2 soil followed by at the summer season and fall season 2015 by the same treatment.
6 - Along growing fall seasons of 2014 and 2015, soil drenching with compost tea exhibited a significant reduction in potato common scab incidence and severity. It was significantly effective to reduce potato common scab incidence and severity . Potato cv. Berna growing in soil under drenching with Nile compost tea at rate (1Kg/M2compost tea: 5 liter water) gave the highest protection. Similarly last potato common scab severity (15%) was expressed by drenching soil with Nile compost tea rate Kg/M2 Nile compost tea: 5 liter water. Al obour compost tea showed significant lowed protection as compared to Al obour compost tea.
7- Concentering foliar spray application of compost tea to potato plants, data showed a significant variances in either DI or DS of common scab caused by Streptomyces scabies isolates CS1. In both season somewhat increase in protection was recorded in fall season of 2015 as compared to 2014 fall season .Meanwhile, increasing compost tea rate increased protection against Streptomyces scabies infection .