ORGANIC POTATO PRODUCTION Table <strong>12</strong>.1.17 Virus Diseases of Potatoes. Disease/Symptoms Spread by Management options Resistant Varieties Notes Major Potato Viruses Potato Leaf Roll Virus (PLRV) Primary infection: upper leaves pale, upright, rolled; lower leaves may be asymptomatic. Secondary infection: lower leaves severely rolled and general plant stunting and chlorosis. Net necrosis on tubers in some varieties. See Cornell photos of primary HUsecondaryUH and HUtuberUH infections (Reference 85) and HUfactsheetUH (Reference 85B). Potato Virus Y (PVY) Symptoms vary, depending on strains and interaction with other viruses, from rugose mosaic, general mosaic, and veinal necrosis to severe necrosis. The common strain = PVY O . The tuber necrotic strain = PVY NTN . See Cornell HUphotoUH (Reference 85B). Potato Virus X (PVX) Plants can show no symptoms and symptoms from an interaction with PVA and PVY. See HUfactsheetUH (Reference 85B). Minor Potato Viruses Potato Virus A (PVA) Symptoms range from mild mosaic to mixed symptoms when interact with other viruses. Potato Viruses S and M (PVS and PVM) See HUfactsheetUH (Reference 85B). Alfalfa Mosaic Virus (AMV) Produces characteristic calico symptoms. See Cornell HUphotoUH (Reference 85) and HUfactsheetUH (Reference 85B). Aphids, tuber seedpieces, volunteer <strong>potato</strong>es and some weed hosts Aphids, tuber seedpiece, volunteer <strong>potato</strong> plants, weed hosts. Tuber seedpiece and mechanical activity. Tobacco, pepper and tomato also host this virus. Aphids, tuber seedpiece, volunteer <strong>potato</strong> plants, some weed hosts Tuber seedpiece and aphids Many aphid species, legume crops and tuber seedpieces Plant phytosanitary certified seed; use stylet oil to limit virus transmission Plant phytosanitary certified seed; use stylet oil to limit virus transmission Plant high quality phytosanitary certified seed. Plant high quality phytosanitary certified seed, use stylet oil to limit virus transmission; plant resistant varieties. Concern when adjacent alfalfa or clover fields are cut and infective aphids fly over to <strong>potato</strong>es. Resistant: Atlantic Moderately resistant: Chieftain and Norland Some varieties are hypersensitive and display field resistance. Some resistance or tolerance: Eva, Dk Red Norland, Belrus, HiLite Russet, Kennebec, Monona, Norwis and Sebago. (Reference 85C). Yukon Gold is very susceptible to PVY NTN . Some varieties with resistance or tolerance are HiLite Russet, Atlantic, Norwis, and Sebago (Reference 85C). Katahdin, Kennebec, Sebago reported to show field resistance. One of the three most important viruses affecting <strong>potato</strong>es. The most prevalent virus infecting <strong>potato</strong>. Can interact with PVA and PVX to create greater yield losses. A widely distributed virus. Often interacts with PVA and PVY, making symptoms difficult to discern. These viruses may be most important when present with other viruses. Does not result in significant yield losses. 5220<strong>12</strong>
ORGANIC POTATO PRODUCTION Table <strong>12</strong>.1.17 Virus Diseases of Potatoes. Disease/Symptoms Spread by Management options Resistant Varieties Notes Potato Spindle Tuber Viroid (PSTV) Tubers are spindle shaped or oblong; plants appear stiff, with unusual upright growth pattern. See Cornell HUphotoUH and HUplant symptomsUH (Reference 85) and HUfactsheetUH (Reference 85B). Tuber seedpiece, mechanically; also through pollen and true seed. Insects can transmit, but not as important. Use certified seed. Viroid has not occurred in NYS for the past 15 years. Potato Mop Top Virus See HUphotoUH (Reference 85B) Powdery Scab pathogen, Spongospora subterranea The virus currently does not occur in NYS, although the fungal vector does. 5320<strong>12</strong>