POLLEN TRANSMISSION OF NECROTIC RING SPOT AND SOUR CHERRY YELLOWS VIRUSES FROM TREE TO TREE

Abstract

Montmorency sour cherry trees, 3 years of age and older, became infected more often with necrotic ring spot virus when exposed during May than when caged individually under 32-mesh screen during May. In screened compartments, necrotic ring spot spread only when bees were present during blossoming. Though necrotic ring spot spread to all but 1 untreated tree in a bearing orchard, it did not spread to neighbouring trees from which blossom buds were removed. Finally, necrotic ring spot virus was transferred to at least 4, and sour cherry yellows virus to at least 1 and possibly a second, of 14 trees that were emasculated and then pollinated with pollen from diseased trees. It is concluded that the viruses causing these diseases are transmitted from one cherry tree to another through pollination.