Apple mosaic virus is one of the oldest known and most widespread apple viruses. The same virus can cause line pattern symptoms in plum and rose mosaic disease. Apple mosaic virus is related to Prunus necrotic ring spot virus.
Apple trees infected with apple mosaic virus develop pale to bright cream spots on spring leaves as they expand (fig. 1). These spots may become necrotic after exposure to summer sun and heat. Most commercial cultivars are affected, but severity of symptoms varies. 'Golden Delicious' and 'Jonathan' are severely affected, whereas 'Winesap' and 'Mclntosh' are only mildly affected. Except in severe cases, infected trees can still produce a crop, with yield reductions varying from no reduction to 50% reduction. In some cultivars, the virus severely affects bud set.
Manage the disease by purchasing virus-tested trees from reputable nurseries.
|Figure 1. Apple mosaic virus symptoms on apple foliage. Photo: E. V. Podleckis.|
Original text prepared by E. V. Podleckis and R. Welliver. The original version of this article appeared in The Mid-Atlantic Orchard Monitoring Guide (NRAES-75) and is reproduced with permission from the Natural Resource, Agriculture, and Engineering Service, Cooperative Extension, 152 Riley-Robb Hall, Ithaca, New York 14853-5701, U.S. A. (607) 255-7654. It has been edited for presentation here by Alan R. Biggs, West Virginia University.