Apple (Malus spp.) - Flat Apple Disease
Cherry (Prunus spp.) - Nematode, Dagger
Cause Cherry rasp leaf virus (CRLV) is readily transmitted by grafting and by dagger nematodes. Several weeds such as dandelion and red raspberry also are hosts. The virus also spreads to apples where it induces flat apple disease. The virus has been found on cherry in eastern Washington and The Dalles OR and on apple in Hood River Oregon.
Symptoms Prominent projections (enations) are found on undersides of leaves. These take the shape of leafy outgrowths or raised protuberances between lateral veins and along the midrib. Leaves are more or less deformed; many are extremely narrow, folded, and distorted. Upper surfaces have a rough, pebbly texture with depressions corresponding to projections on the lower surface. Not all parts of a tree show symptoms at the same time. Early infections usually are limited to low branches. Spread is slow within a tree and between trees. Fruit production is reduced. Severely affected branches and young trees may die.
- Use nursery stock that has been tested and found to be free of all known viruses.
- Remove infected trees as soon as symptoms are seen.
- Control the nematode vector.
- Thermo therapy has been effective in apple.
Reference Hadidi, A., Barba, M., Candresse, T., and Jelkmann, W. 2011. Virus and Virus-like Diseases of Pome and Stone Fruits. St. Paul, MN: APS Press.