Insect transmission of virus between tree and herbaceous plants

Abstract

Four virus strains, peach yellow leaf roll virus, Napa buckskin virus, Green Valley buckskin virus and a related strain, were transmitted experimentally to celery ( Apium graveolens) by means of the leafhopper vector, Colladonus geminatus. In celery, all four viruses induced similar disease symptoms 4 to 6 weeks after infection. The first symptoms consisted of chlorosis of the youngest leaves and stiffening of the oldest leaves. With the onset of symptoms, growth almost ceased, particularly in the heart of the plant. Within a few weeks thereafter, the entire plants became chlorotic, the root systems collapsed, the shoots became flaccid, and the plants died. In all, 94 of 108 tested celery plants developed disease symptoms. Previously nonviruliferous leafhoppers acquired yellow leaf roll virus from diseased celery plants and transmitted it to 89 of 106 tested peach trees which developed typical symptoms of yellow leaf roll disease. The high percentage of virus transmission from celery to peach, after a relatively short acquisition feeding period of 3 days, suggests that infected celery may be a better virus source than peach for the leafhopper vector. Peach yellow leaf roll virus is considered to be a strain rather than a distinct virus, on the basis of virus-vector relationships, symptoms, hosts, and cross protection. Western aster yellows virus failed to produce symptoms in any of 54 peach trees fed on by viruliferous leafhoppers, while the same leafhoppers infected 9 of 9 celery plants tested.