New Test For Cucumber Mosaic Virus

Cucumber mosaic virus infects more than 800 species of plants worldwide, causing losses both in the United States and overseas. Now a new, commercially available test will allow growers, producers and exporters to track both foreign and domestic strains. That could mean improved outbreak prevention or control.

The test kit, developed in cooperation with the U.S. National Arboretum's Floral and Nursery Plants Research Unit, is available through Agdia, Inc., of Elkhart, Ind. The arboretum is part of USDA's Agricultural Research Service.

Earlier, the ARS scientists, based in Beltsville, Md., collected more than 140 cucumber mosaic virus (CMV) strains, including ones from Russia, South Africa and Southeast Asia. They developed unique antibodies that react to strains found in both the United States and abroad, then used those antibodies as the basis for a comprehensive test to detect CMV.

Agdia commercialized the test in cooperation with the ARS scientists. The test is based on sophisticated biochemistry, but is easy to use. Farmers and nursery operators simply touch a newly cut leaf or stem of a plant they want to test to a specially treated, paper-like membrane. The plant does not have to show any symptoms or visible signs of the disease.

The membrane is taken to an extension office or laboratory and treated with solutions that contain mouse antibodies that react to the virus. Next, solutions are used that cause a change in color at the "touched spot" if CMV is present. Uprooting and removing the infected plants then helps prevent the spread of the virus in the crop.

Despite its name, CMV doesn't attack just cucumbers. In 1992, it plagued tomato crops in Blount and St. Clair counties in Alabama, forcing some growers out of business. Quicker detection might have saved some of these farms.

The test can be used for general detection of CMV or adapted to look for specific CMV subgroups. Subgroup I is common in North America; subgroup II is prevalent in the Tropics. The test might someday be used to monitor plant imports and exports for the virus.

Scientific contact: Hei-Ti Hsu, ARS Floral and Nursery Plants Research Unit, Beltsville, MD 20705, phone (301) 504-5657, fax (301) 504-5096. hthsu@asrr.arsusda.gov.