streptomyces scabies can infect many plants, but is most commonly encountered causing disease on tuber and tap root crops. it causes common scab on potato (solanum tuberosum), beet (beta vulgaris), carrot (daucus carota), parsnip (pastinaca sativa), radish (raphanus sativus), rutabaga (brassica napobrassica) and turnip (brassica rapa). it also inhibits the growth of the seedlings of both monocot and dicot plants. potato varieties differ in their susceptibility to s. scabies. more resistant varieties tending to have fewer, tougher lenticels and a thicker skin, although authors do not agree on the specific characteristics required for resistance.