Impact of the sowing environment and irrigation level on black scurf development in potato (Solanum tuberosum L.)

Black scurf disease caused by Rhizoctonia solani Kuhn is a major problem worldwide. The incidence of black scurf disease in potato is significantly influenced by the date of planting and irrigation level. Cultural practices such as the planting of tubers and irrigation produce variable effects on the incidence and severity of black scurf disease in potato by modifying its soil microclimate such as soil temperature and moisture. As the date of planting has increased, the disease incidence and severity have increased. The minimum disease incidence and disease severity were detected in early-sowing infected tubers, whereas maximum disease incidence and severity were detected in late sowing tubers. Among the different irrigation levels in during first year and second year of investigation, the 20 mm CPE treatment resulted in significantly greater disease incidence (63.50 and 63.84%) and severity (43.33 and 42.50%), followed by 25 mm CPE treatment (incidence 56.50 and 54.00% and severity of 32.50 and 32.50%) and these differences were statistically significant. The lowest percentages of disease incidence (50.00 and 45.33%) and severity (30.00 and 29.17%) were recorded at the 30 mm CPE irrigation level.