Abstract
Leaf juice of Japanese black pine (Pinus thunbergii Parl.) inhibited turnip mosaic virus (TuMV) infection when radish and Chenopodium amaranticolor were inoculated with the virus 24 hours after spraying the juice on the plant. Some inhibition was observed even when the juice was sprayed 7 days before virus inoculation. The inhibitory effect of the juice was about equal in younger leaves and in older leaves of the pine.
The inhibitory effect was observed also with juice extracted from cone and bark of young twig of Japanese black pine. While some inhibitory effect was observed when the juice was sprayed on C. amaranticolor one hour after virus inoculation, there was no inhibitory effect when radish plants were sprayed with the juice 24 hours before inoculating the virus by Myzus persicae. The inhibition became slighter when the test plants were heavily sprinkled with water 2 hours after juice spraying.
