Plant pathologist Robert Martin grafts a strawberry plant to an indicator plant to determine whether any viruses are present. Click the image for more information about it.

Above, leaves and stems of a strawberry plant infected by five viruses including strawberry latent ringspot. Below, a mint plant—sold widely as an ornamental—infected by the ringspot virus and two others.

Strawberry Latent Ringspot Virus Found in North America

By David Elstein
February 18, 2005

Strawberry latent ringspot virus, a problem for the past 30 to 40 years in Europe, has just been discovered in North America by Agricultural Research Service (ARS) scientists and cooperators.

Scientists with ARS, Oregon State University, and Elmhirst Diagnostics and Research of British Columbia found the virus on 17 percent of the California strawberry samples and on four percent of British Columbia strawberries. The virus was also found in a variegated mint.

The virus, which can dramatically decrease yields, is spread by nematodes, so the scientists were surprised to find the virus in California strawberries, as most are planted in pre-fumigated soil.

Plant pathologist Robert R. Martin of the ARS Horticultural Crops Research Unit in Corvallis, Ore., is leading the agency's efforts in studying and preventing the virus.

The group discovered the virus by doing a broad-spectrum test to look for viruses that may be involved in strawberry decline and variegation of mint. They compared nucleic acid and protein sequences of the virus from strawberry and mint to those in databases.

The scientists believe that the virus has been in this country for many years on an ornamental mint sold throughout the United States--popular because of its bright-yellow color--without anyone noticing. It turns out that the color partially comes from the ringspot virus.

Many of the chemicals that have been used to control this and other viruses transmitted by nematodes are being pulled from the market because of environmental concerns. Martin and ARS colleague Jack Pinkerton are studying alternative ways to control nematode-transmitted viruses, such as rotating a crop that is not a host for the virus so that the nematodes lose the virus and are no longer able to transmit it.

While the virus has only been found on mint and strawberries in the United States, it can infect many broadleaf crops.

ARS is the U.S. Department of Agriculture's chief scientific research agency.