Pest plagues Ontario's garlic crop

Thursday, March 1, 2012

Foodland Ontario photo

by SUSAN MANN

Seventy-three per cent of the garlic samples collected as part of a project to determine the extent of bulb and stem nematode in Ontario have the pest, says a University of Guelph researcher.

“We weren’t expecting quite that high a number of positives,” says Becky Hughes, manager of the SPUD (Superior Plants Upgrading and Distribution) unit at the university’s New Liskeard facility. According to a provincial fact sheet, the pest is a “tiny microscopic eel worm that lives within plants, feeding on stems, leaves, and bulbs.”

One of the project’s next steps is to identify the races involved. There are more than 30 races of bulb and stem nematode and they attack different plants. There are 400 to 500 species of plants this nematode can attack, she explains.

Hughes says the test to identify the races is very time consuming. But they should have those results by sometime this summer.

Growers are also being informed of the results. Growers who submitted samples got their individual results already and researchers have given talks at three grower meetings so far to release collective data. One more information meeting is coming up on March 24.

There are also plans to hold workshops later in the year to inform growers how to grow clean seed and how to keep it clean.

“A big purpose of this project was grower awareness – to make growers realize there is a problem out there so they can recognize the symptoms,” she says. But that can be difficult because the symptoms of bulb and stem nematode are very similar to some of the soil-borne diseases of garlic.

A garlic clove infected with bulb and stem nematode will grow a short stunted stem and leaf and will die early. When the bulb dies it releases chemicals that are toxic to the nematode so the pest leaves the bulb and goes out in the soil looking for other garlic.

The project began last spring with researchers collecting samples. In total they collected 123 samples from 79 growers located in 33 counties or districts across Ontario, from the Quebec-Ontario border in the east, to Temiskaming and Algoma in the north, and south to Kent County.

“We got a pretty good representation” across the province, she says, noting they didn’t reach all growers in all areas.

Hughes says at her lab in New Liskeard they’re growing clean seed from tissue-cultured plants for the garlic growers association. The seed is free of nematodes, viruses and diseases. The seed was distributed in the fall and researchers will be doing follow-up testing this summer to see if it becomes infected.

The project will wrap up by the end of August because that’s when the funding ends, Hughes says. In addition to the university, other supporters of the project are the Garlic Growers Association of Ontario, the provincial agriculture ministry and Agriculture and Agri-Food Canada. BF