Tuesday, July 13, 2010

Is your sweet cherry tree infected by a virus?

When sweet cherry leaves have a small leaf growing out of a vein, the tree has cherry rasp leaf. This unusual outgrowth is called an enation, literally meaning ‘small leaf’.

When your cherry tree exhibits these outgrowths, enjoy it while you can because it won’t be around very long. It will die! There is no cure once the tree is infected.

The virus is spread by dagger nematodes, Xiphinema americanum, by budding and grafting, and by root grafts. As with other nematode-vectored virus diseases, the symptoms appear on one or a couple trees in the orchard and spread outward in a circular pattern. This spread is due to the movement of infected nematodes and the natural grafting of roots between infected trees and non-infected trees. There is evidence of pollen from a virus-infected tree spreading the virus as well.

If you plant another sweet cherry tree in the same area within two years, you can expect your new tree to be infected due to the presence of virus-infected Xiphinema americanum in the soil. If you plant an apple tree during that time, it is likely to suffer from “flat apple” syndrome, if you plant a peach tree it may be infected but not show symptoms serving as a “Typhoid Mary” resulting in the infection of other trees. Field bindweed, dandelion, plantain and lambsquarter also serve as hosts for this virus and thus should be eradicated if anywhere near your backyard or commercial orchard.

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