Garlic growers await nematode research outcome

Wednesday, June 15, 2011

by SUSAN MANN

Ontario’s garlic growers will have a better handle on how bad a problem stem and bulb nematode is in the province by the fall.

That’s when researchers from Ontario’s agriculture ministry, the federal government and the University of Guelph will have analyzed samples submitted by garlic growers this spring as part of a two-year project to determine preventative measures and practices for stem and bulb nematode. The Garlic Growers Association of Ontario received about $70,000 in funding from the Agricultural Biosecurity program for the project.

Association president Mark Wales says they know stem and bulb nematode has been around for some time and it’s a problem in other garlic-growing regions and that’s why the Ontario industry has been working toward a clean seed program for several years. “As we’re getting clean, disease-free seed we want to make sure farmers know where to plant it and where not to plant it.”

Farmers with nematode-infested fields shouldn’t plant garlic in them for four to five years. Instead, they should plant crops that aren’t host crops for nematodes. “And you should figure out other treatment possibilities,” he explains.

The project has three objectives. One is to determine how geographically extensive stem and bulb nematode is in the province and to identify the race or races that are present. Another is to verify that the nematode-free virus-tested seed production system developed by the University of Guelph in 2010 is repeatable and to determine the cost of seed. The third is to educate growers through workshops on the spread, symptoms, biology and control of the pest.

Marion Paibomesai, Ontario agriculture ministry vegetable crop specialist, says they’re hoping to collect 200 samples from across Ontario for analysis. “We’re trying to find out where it is and what races we’re dealing with here.”

It’s important to determine the race of the stem and bulb nematode because there are more than 30 biological races of the species, she says. Each race has a specific host range. “We want to know that if we find some on garlic is it a race that we’re going to find too on alfalfa?”

For crop rotation, it’s really important to know the race, she says.

Wales says it’s important to know the extent of the infestation because “sometimes the damage gets mistaken for other things.”

Paibomesai says the stem and bulb nematode is occasionally confused with fusarium basal rot.

Stem and bulb nematode in garlic attacks the base of the bulb and then gets in and sucks out the juice. The result is small, deformed or totally destroyed bulbs, Wales notes.

Nematodes attack the root hairs of other crops, such as strawberries and tobacco. Stem and bulb nematodes attack other crops in the allium family, such as onions, shallots and leeks.

Wales says the garlic industry has been working on a clean seed program for several years. Some growers received clean seed last fall that they planted and “it’s looking great.” BF