b'TATER TALES What Growers Can Do to Limit PVY SpreadExcerpts from Mathuresh Singhs presentation at the 2023 Ontario Potato Conference.POTATO VIRUS Y (PVY) has re-emerged over theof most potato varieties. Sometimes this appears as a last decade as a serious, yield-limiting viral diseaseroughening of the leaves. The necrotic strain PVYNTN thats a threat to potato production worldwide.causes milder mosaic in the leaves, but does lead The virus infects many crop species in the familyto tuber necrosis in susceptible potato varieties, a Solanaceae, and infected seed is the most importantcondition referred to as potato tuber necrotic ringspot source of inoculum in potato fields. Infection levelsdisease (PTNRD). All strains cause a reduction in yield (two to three per cent) dont usually cause problems, the necrotic strains make the tubers unmarketable. but this is a virus that spreads easily in infected tubers,The virus is transmitted when an aphid probes by plant sap and aphids, including those that dontthe plants. This brief taste testing lasts from several EUGENIA BANKS,colonize potatoes. Cutting infected seed doesnt moveseconds to several minutes. Its long enough for aphids potato specialistPVY from infected seed to healthy ones. Mechanicalto acquire the virus and to inoculate healthy plants if with the Ontariotransmission during the season is caused by tractorsthe aphids have fed on an infected plant previously. Potato Boardand sprayers. Growers have every reason to bePVY is difficult to control because acquisition and concerned. infection happen so rapidly. Insecticides may help to PVY is an evolving cluster of genetically relatedreduce aphid numbers in a field but aphids entering multiple strains. Symptoms vary with the strain,from other fields have enough time to spread of virus the variety, and the growing conditions. There is abecause no insecticide acts quickly enough during common strain PVYo that causes mosaic on the leavestaste testing. Circles of dead plants caused by green peach aphid.PHOTO: EUGENIA BANKS44SPUDSMART.COM Spring 2023'