Apple mosaic virus
Apple mosaic virus (ApMV)
Young leaves develop pale to bright cream-colored spots, blotches, bandings or patterns as they expand in the spring (A). These turn brown and become necrotic as they age and premature defoliation may occur when infection is severe. Symptom expression is highly variable among varieties.
Common to all fruit-growing regions in eastern North America.
The virus is exclusively mechanically transmitted; i.e., there are no known insect vectors. Therefore, ApMV can be avoided by planting trees that are certified virus-free. Transmission can occur in the orchard through root grafts; roguing infected trees will limit the spread. Almost all varieties are susceptible to the virus, but some express symptoms more readily than others. Golden Delicious, Granny Smith and Jonathan are very susceptible; McIntosh is moderately susceptible. Infected trees may still produce a good crop.
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.