A SURVEY OF BLACK DOT AND OTHER FUNGAL TUBER BLEMISHING DISEASES IN BRITISH POTATO CROPS AT HARVEST

Black dot and other fungal blemishing diseases were assessed on tubers from crops in eastern England in 1987 and 1988, and in 1989 and 1990 from crops throughout Great Britain. Black dot was found on tubers in crops from all areas of the country, and was most common in those from eastern and southern England. The disease was scarce on most Scottish crops, but occasionally some were severely affected. In 1988 there wa s no consistent relationship between the amounts of disease on the see d and subsequent ware crop. On average, the disease was more prevalent in irrigated crops and where the interval between successive potato c rops was short. In 1990 treating seed tubers with fungicide had no eff ect on subsequent levels of disease. Few crops were unaffected by silv er scurf, and it was most common in crops from southern and eastern En gland. In the national survey common scab was the most prevalent disea se, black scurf was less common and skin spot and powdery scab uncommo n except in some Scottish crops.