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October 18, 2001

CNG SEEKS SOLUTIONS TO LEAFY SPURGE

According to some estimates, leafy spurge infestation in Manitoba has increased dramatically from about 220,000 acres in 1985 to an estimated 340,000 acres today.

Much of the infestation is in the southwestern part of the province. Covering New Ground (CNG), Manitoba's Agricultural Sustainability Initiative, is funding a project near the community of Medora designed to examine methods of controlling leafy spurge in Manitoba pastures.

"Leafy spurge is a big problem and it is a growing issue," said Shane Dobson, ag rep in Melita. "There are areas in my district where leafy spurge is literally taking over pastures. And it's not just a southwestern Manitoba problem. There are thousands of acres in North Dakota invaded by the weed.

Alberta and Saskatchewan have their problems too." Dobson believes overgrazing is one reason the problem is spreading. It seems, he said, that a good, strong pasture helps keep the leafy spurge down.

"There really isn't any acceptable chemical solution to the problem," said Bonnie Maynard, weed supervisor for the area. "Anything that has an effect on it, such as Tordon 22K, has residual affects and can cause concern if shallow groundwater exists. "Most sites are too rough to spray from the ground," she added, "and aerial spraying of Tordon is not registered. Used twice a year, 2,4-D can knock it back for a while, but it doesn't eliminate the problem in the longer term."

A 160-acre demonstration site has been established north of Medora to examine methods of controlling the weed. The project, under CNG funding, has focused on control methods using beetles and moths during its first year.

"Early in July, we released two species of beetles on different locations at the site," said Maynard, who is in charge of the project. "Aphthona nigriscutis (black dot spurge) beetles were released at six sites and Aphthona lacertosa (brown-legged spurge) beetles at one site."

Up to 5,000 beetles were released at each location. Maynard said it is still too early to draw any conclusions, because the beetle larvae attack the root system of the plant and the impact won't be seen until spring. The sites will be monitored by conducting stem counts and looking for evidence of damage to the plants.

Leaf roller moths were also established at a separate location on the quarter section of land in late July. Moth larvae feed on the flowers, preventing seed set. The impact of the larvae will be difficult to quantify because it doesn't kill any plants. It just prevents new ones from starting. The moths were collected near Shilo by cutting cocoons from growing plants with scissors.

"We actually taped the cocoons to the plants at our site with electrician's tape!" Maynard said. "Anyone driving by and seeing us must have wondered what we were doing."

Next year, multi-species grazing using sheep and goats will also be examined as a leafy spurge control method at the site. While cattle avoid eating leafy spurge, sheep will graze on it and goats seem to prefer it.

"Paddocks will be built and we will graze sheep in one and goats in another," Maynard explained. "But there is no one living at the site and predators, especially coyotes, are a problem. We intend to use portable corral panels and leave the animals out only for short periods of time to protect them as much as we can."

Leafy spurge was introduced to North America in the late 1820s, apparently arriving in Massachusetts either in a grain shipment or as part of a ship's ballast. It was first identified in Canada in 1889. A 40 per cent infestation of leafy spurge can reduce the grazing capacity of a pasture by as much as 50 per cent.

Related projects have been carried out by WESTARC, Pembina Soil and Crop Management Association Inc. and the Stanley Soil Management Association. For more information on these projects or the Covering New Ground Program,contact your regional soil and water management specialist or visit the web site at <http://www.gov.mb.ca/agriculture/research/covering/> www.gov.mb.ca/agriculture/research/covering/.

Editors note: This is the first in a series of news releases on agricultural sustainability produced by Covering New Ground, a program that funds local projects to help find economical solutions to environmental challenges in Manitoba's agricultural community.