SPRING RUSTS IN YOUR RIBES?

Kim E. Hummer 11 May 1998

Are your currants and gooseberries rust showing signs of rust fungus in the spring? There's a good chance they are suffering from CLUSTER CUP RUST, Puccinia caricina D.C.

This rust is native to the Northern Hemisphere and requires a Ribes and a sedge (Carex) as alternate obligate hosts. Symptoms of this rust appear in late April or May in as yellow spores on the under and upper surfaces of currant or gooseberry leaves or on the young developing fruits. These yellow spores, which are known as aeciospores, become windborne and infect a nearby sedge. In moist years this disease can seriously reduce the Ribes yield. This disease is worst in the neighborhood of wet or marshy areas where sedges abound (Gardner, 1976). In some cases sedges can be removed to reduce the effect of the rust. The best precaution is to avoid planting Ribes in low-lying wet areas. Gardner (1976) states that "the disease is seldom serious enough to warrant special control measures."

Cluster cup rust has been observed specifically in the following states: Alaska, California, Illinois, Idaho, Mississippi, Montana, New York, North Dakota, Oklahoma, Oregon, South Dakota, Vermont, Washington, Wisconsin, Wyoming (Farr et al., 1989). Farr et al. (1989) also list it as occurring, generally, in the northeast and north central states.

References:

Farr, D. F., G. F. Bills, G. P. Chamuris, A. Y. Rossman. (eds.) 1989. Fungi on Plants and Plant Products in the United States. APS Press. St. Paul, Minn.

Gardner, R. 1976. Bush Fruits. Ministry of Agriculture, Fisheries and Food. Ref. Book 4. London.