Strawberry viruses spread by aphids are on the rise

Friday, August 9, 2013

by SUSAN MANN

Combinations of two or more viruses are causing plants to decline and economic damage for some Ontario strawberry growers.

Kevin Schooley, executive director, of the Ontario Berry Growers Association, says one virus on its own doesn’t “seem to have an economic impact but when you combine two or more viruses that is where you’re seeing problems.”

A federally funded survey last year coordinated by Ontario Ministry of Agriculture and Food berry specialist Pam Fisher found that 87 per cent of samples obtained from most areas of the province had one or more viruses. Schooley didn’t have the total number of samples that were taken. The association applied for the funding to do the survey and helped to coordinate it.

Schooley says the viruses causing problems are: strawberry mottle virus, strawberry vein banding virus and pallidosis virus. Visible symptoms include plants lacking the same vigour as ones without virus, distorted or discoloured leaves, misshapen and small fruit, and reduced yield. The viruses don’t affect the taste or health of the fruit and don’t pose a risk to human health.

In most cases the viruses are spread by aphids, particularly strawberry aphids. This particular aphid has a limited number of host plants it feeds on, including wild and commercially produced strawberries and some weeds. That makes the situation a “little bit more manageable,” he says.

The virus problem is fairly new to Ontario but it has hit other areas, including California, British Columbia and Europe. In those areas “they’ve made a conscious effort in controlling aphids and making sure that their plant supplier has clean plants,” he says. Another suggestion is to remove all affected plants, plant fresh new stock and control aphids “so that you don’t get continued spread of the virus.”

Farmers in those areas have been able to manage the problem and clean up their strawberry fields “pretty well,” he adds.

An area of Nova Scotia was hard hit by viruses this year and that’s drawing attention to the problem, Schooley says. The virus problem in Ontario overall isn’t as bad as in Nova Scotia. But some individual farmers in Ontario were “extremely hard hit,” he says.

Farmers have been told about the problem and Schooley says many are aware of it and are tacking action to control aphids and manage their plantings. “But I think after what has happened in Nova Scotia and now with some of the challenges that growers have had here in Ontario, I think hopefully everyone will take it very seriously,” he adds. BF