16 April, 2019
Answer: Sharka virus was confirmed in Adams County, Pennsylvania—the first outbreak in North America. The disease has since been found in Cumberland County, Pennsylvania, and in Canada. This has caused much concern among producers because plum pox is an exceptionally destructive disease of stonefruit. Infected fruit are unmarketable because of spots and ring blemishes, and fruit may also drop prematurely. Plum pox is transmitted either by aphids or by grafting. The disease was not found in nursery stock, and an ongoing quarantine has apparently contained the outbreak of plum pox to a limited area, although testing is ongoing.