Union Necrosis and Decline

Apple trees show unthrifty growth, abnormally high fruit set, and a dark necrotic line at the graft union when infected with tomato ringspot virus. The virus spreads via dagger nematodes in eastern North America and occasionally in the PNW. Plant virus-tested trees in disease-free sites. Roguing young orchards prevents further spread.

Primary control is by planting virus-tested (and found to be free of all known viruses) trees and in sites that have no history of the disease.