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News
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No cause for alarm as tansy ragwort resurges in Oregon
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8/10/2011
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Article Content Suggested lead
For the past couple of summers, Oregon farmers and ranchers have noticed the bright yellow flowers of tansy ragwort, the noxious weed once the scourge of the 1970s. But state weed control officials say there is no cause for alarm:
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Just like a year ago, patches of tansy ragwort are emerging right now. That may bring back bad memories from decades ago of livestock dying due to tansy poisoning. That's when the Oregon Department of Agriculture successfully launched a biological control program using good insects to defeat a bad weed:
COOMBS: "The biocontrol agents don't always kill the tansy directly, but they weaken it so much that it makes it almost impossible for it, under normal circumstances, to compete for water and nutrients." :11
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ODA entomologist Eric Coombs says despite what appears to be a bit of a resurgence the past few years, he's confident the flea beetle and cinnabar moth will build up populations to the point where they will control the weed:
COOMBS: "I think we've done our job. Now it's time to let the insects do their job. It's a natural cycle. They are part of the environment now. We will get these little flare-ups. It will always be kind of a popcorn thing where it's here and there, then it will move around from field to field depending on the use of the field, depending on the weather." :17
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As the tansy ragwort population grows, so does the number of insects that act as natural predators in noxious weeds. Officials are hopeful for a much more manageable tansy problem over the next couple of years. In Salem, I'm Bruce Pokarney.
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COOMBS says Oregon's tansy ragwort problem is cyclical and as the population of weeds grows, so does the population of the biocontrol agents:
"The plant numbers have been low, the insect numbers are low. So it's going to be probably a year or so- maybe more in some places depending on the land use- before the insects build up in numbers and knock the weed back down." :12
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Full story
http://oregon.gov/ODA/news/110810tansy.shtml |
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