SUSCEPTIBILITY TO PHYTOPHTHORA-INFESTANS OF FIELD-GROWN AND GLASSHOUSE-GROWN POTATO-TUBERS

Tests for resistance to Phytophthora infestans were done twice in each of 2 years on field- and glasshouse-grown tubers of ten cultivars. Th e cultivar rankings were almost identical for the means of the four gl asshouse tests and the means of the four field tests. However, for the field tests but not for the glasshouse tests there were cultivar x ha rvest date and cultivar x year interactions. It is concluded that resi stance can be assessed on glasshouse-grown tubers and that such assess ments should prove more consistent over years than those done on field -grown tubers.