Why PVY can no longer be controlled in seed potatoes
Jeff Davis, email@example.com, David W. Ragsdale, firstname.lastname@example.org, and Ted Radcliffe, email@example.com. University of Minnesota, Department of Entomology, 1980 Folwell Ave, St. Paul, MN
North American seed potato producers have experienced an unprecedented and now decade-long Potato virus Y (PVY) epidemic. In 1995, Minnesota and North Dakota produced 20,000 ha of seed potatoes and provided 40% of the seed entering interstate commerce. In 2005, Minnesota and North Dakota produced only 8700 ha of certified seed potatoes mostly due to the inability to control PVY. Factors involved include the recent establishment of a new vector of PVY, soybean aphid, Aphis glycines Matsumura, and the prevalence of new strains of PVY, especially PVYN:O. We have shown that soybean aphid is a capable vector of all PVY strains transmitting at 33% efficiency. In 2005, 2100 leaf samples from 325 MN potato seed lots show that PVYN:O is now the dominant strain (56%). PVYN:O is difficult to detect visually demonstrated by a reduction in confirmation of visual infection using ELISA from 83% in 2002 to 50% in 2004. Since few seed lots are entirely PVY-free when planted, cultural techniques to limit PVY spread such as crop borders and mineral oils are now less effective. Field research showed no significant reductions in PVY spread when crop borders or mineral oils were applied (P-value=0.335 and 0.299, respectively) when initial inoculum levels exceeded 7%. The failure of potato seed certification programs to end the PVY epidemic shows that PVY can no longer be reliably visually detected and cultural practices that have been effective in the past are no longer able to control PVY spread.
Species 1: Hemiptera Aphididae Myzuspersicae (green peach aphid) Species 2: Hemiptera Aphididae Rhopalosiphumpadi (bird cherry-oat aphid) Species 3: Hemiptera Aphididae Aphisglycines (soybean aphid)