Development of common scab in potato cv. Kufri Pukhraj in Indian Punjab is influenced by scab lesion severity on seed tubers and duration of crop in the field.

The intensity of scab caused by Streptomyces scabies on mother seed tubers significantly impacts the scab severity in the harvested crop. In the current study, it is revealed that scab severity on infected mother seed tubers and duration of crop directly affects the disease severity in progeny crop. Mother seed tubers with disease severity grade of 0, 1, 2, and 3 were sown with different crop duration periods of 70, 80 and 90 days. Significantly greater disease incidence and severity were recorded when seed tubers of infection grades 2 and 3 were sown (59.41 and 64.26% incidence; 6.7 and 7.2% severity, respectively). Significantly lesser scab incidence and severity were recorded at 70 DAP (35.64 and 2.4%, respectively) than at 80 and 90 DAP. It was also found that the disease incidence in 80 and 90 days old crop from mother seed tuber of infection grade 0 was statistically similar to disease incidence in 70/80/90 days old crop of mother seed tubers with infection grade of 2 and 3. Significantly maximum lesion grade was found in 90 days old crop sown from mother seed with scab severity grade 3. This shows that the scab incidence and severity increases in the crop with increase in the disease severity grades of mother seed tubers and increased duration of crop by delaying the harvesting interval. Hence, the strategy of planting seed tubers with minimum scab severity grade and harvesting the crop earlier, preferably at 70 DAP, can be utilized to lower the disease severity in progeny crop. [ABSTRACT FROM AUTHOR]