TRANSMISSION OF PRUNUS NECROTIC RINGSPOT VIRUS USING PLUM POLLEN AND THRIPS

Prunus necrotic ringspot virus (PNRSV) was transmitted to cucumber but not to peach seedlings after they were dusted with infective plum pollen and caged with 8 - 10 thrips per seedling for 24 h. When the pollen was taken from three plum trees shown by mechanical inoculation tests to have highly infective flower buds and pollen, the transmission rates to cucumber seedlings were 56% with Thrips tabaci and 66% with a mixture of five thrips species collected from Ageratum houstonianum flowers. However, the transmission rate averaged only 7% when pollen was taken from five other plum trees which had flowers with less infectivity in sap transmission tests. In 1990 T. imaginis, T. tabaci and T. australis, which were present in the mixture of thrips from A. houstonianum, also formed the major part of the thrips population in flowers of the plum trees used as the pollen source.