Cucurbit Genetics Cooperative Report 7:80 (article 35) 1984

Further occurrence of Zucchini Yellow Mosaic Virus in the United States

Provvidenti, R. and D. Gonsalves

New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456

H.S. Humaydan

Joseph Harris Company, Inc., Rochester, NY 14624

During 1983 zucchini yellow mosaic virus (ZYMV) occurred in cucurbits grown in New York, Florida and California. In affected fields the virus caused severe losses in fruit production.

It appears that at least two strains of ZYMV are present in the United States. The first strain designated ZYMV-CT was found to infect squash in northern Connecticut in 1982 (3) and was subsequently isolated from squash specimens collected in the fall of the same year at Homestead, FL. This strain causes very severe yellow mosaic, knobbed fruits and plant stunting. These symptoms closely resemble those described for the European isolate of the virus (1,2). The second strain (ZYMV-FL) was originally isolated from squash growing in central Florida in the winter of 1982-83, and subsequently in 1983 from cucurbits grown in western New York and central California. ZYMV-FL incited symptoms that could be easily confused with those of watermelon mosaic virus 1 (WMV-1) infection. Foliage symptoms are also severe but they lack the intense yellowing caused by ZYMV-CT. However, plants are also stunted and fruits are knobbed. Both strains have the same host range and serologically are indistinguishable, but the incubation period of ZYMV-FL is 3-5 days longer. An antiserum was prepared to cytoplasmic inclusion proteins (CIP) of ZYMV-CT. This antiserum reacts with the American and foreign isolates of ZYMV, but not with the CIP of WMV-1 or WMV-2.

The destructive epidemics caused by ZYMV, here and abroad, illustrate the economic importance of this virus. Thus, our activity has been directed toward the search for sources of resistance or tolerance in cucurbit species. Utilizing hundreds of domestic and foreign cultivars, it has been established that, although rare, resistance or tolerance occurs in a few accessions of Citrullus colocynthis. Cucumis melo, Cucumis sativus, Cucurbita ecuadorensis, C. maxima and Lagenaria siceraria.

Literature Cited

1. Lecoq, H., M. Pitrat, and M. Clement. 1981. Identification et characterisation d'un potyvirus provoquant la maladie du rabougrissement jaune du melon. Agronomie 1:827-834.
2. Lisa, V., G. Boccardo, G. D'Agostino, G. Dellavalle, and M. D'Aquino. 1981. Characterization of a potyvirus that causes zucchini yellow mosaic virus. Phytopathology 71:667-672.
3. Provvidenti, R., D. Gonsalves, and H. S. Humaydan. 1983. Occurrence of zucchini yellow mosaic virus in the United States. Cucurbit Genetics Coop. Rept. 6:99.