Production of black leg and soft rot free potato.
Zohur, Esfandiyar | Rahimiyan, Heshmat Ol-Lah
In the present study several strains of Erwinia carotovora subsp carotovora (Ecc) and E.carotovora subsp atroseptica (Eca) were iso lated from potato tubers in the different regions of Khorasan ,Hamadan ,Fars and Ardabil .They were pathogenic on potatoes .Efforts have been made to characterize The taxonomic structure of erwinas throughout the world. The phenotypic features of several strains of Ecc and Eca in Iran are not well in accord with the different characteristics set up by investigators for these subspecies. These two subspecies appear to have a cosiderable heterogeneity in Iran. In the present study strains of pectolytic erwinias were isolated from several regions and their phenotypic features, and electrophoretic patterns of cell proteins were compared. Strains were gram negative ,rod shaped, and motile with peritrichous flagella. Their optimum tempreatures for growth were 27-30 oc .All strains produced acid from fructose, glucose,D-galactose and sucrose, and rotted potato tuber slices.All strains were positive in production of H S from cystein,and nitrate reduction but were urease negative .They utilized Lactose,raffinose,arabinose and produced acid from them.Therefore the strain were considered to be members of soft rot group. The majority of the isolates produced acid from xylose,rhamnose, salicin, sorbitol,melibiose, trehalose and cellobiose and utilized lactate acetate and citrate. Some cultural practices which are effective on black leg disease in production of diseasefree seeds were studied in a field experiment applying strip plot method under randomized complete block. Design with three factors replicated four times.these factors included weed control (Stress),soil freezing (irrigation in winter) in winter) and soil air condition. According to Duncan's new multiple rang test moisture stress had maximum effect on disease infection level so that minimum infection was found in mouldboared plough without moisture stress treatment while the lowest infection was recorded in case of mouldboared plough plus moisture stress.
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