Working together to strengthen and support noxious weed management efforts in Montana.

Tansy Ragwort on the Rise in Oregon

Monday, August 15th, 2011

The following is an excerpt from Eric Coombs at the  Oregon Department of Agriculture.

What is going on?

There is a growing concern in western Oregon, and that concern is Tansy Ragwort. It seems to be rearing its ugly head (maybe pretty to some) in numerous areas in western Oregon. People want to know what to do about it. Why have the biocontrol agents like the cinnabar moth and flea beetle failed to control it? Will we have economic losses to our livestock again, as occurred in the 1960-70s?

Oregon enjoyed a long-term success in the mid-1980s through 2005 of not having a lot of tansy ragwort around, to the tune of 5 million dollars a year in economic benefits to Oregon agriculture. Tansy ragwort is a biennial plant in the sunflower family that was unintentionally introduced into Oregon in the early 1920s, and within 30 years, became a regional problem, killing thousands of livestock animals – mostly cattle and horses, and contaminating pastures and hay. By the 1970s, many pastures, hillsides, and log clearings were invaded and heavily infested by tansy ragwort. Tansy is mostly a weed that gets a foothold in plant communities that have been disturbed, either by grazing, logging, construction, fire etc. Unless you have livestock, tansy is more of a symptom of a problem than a problem. The Oregon legislature commission the Oregon Department of Agriculture (ODA) to implement a biological control program to control tansy ragwort. Three insects, the cinnabar moth, a flea beetle, and a seed head fly were introduced from 1960-1971. These insects are natural enemies of tansy ragwort that were tested for host specificity and imported from tansy’s homeland in Western Europe. Once they were established in Oregon, ODA began an intensive redistribution program, collecting and releasing millions of the biocontrol agents at infested sites throughout the state. By the mid-1980s, tansy infestations were in sharp decline and cattle deaths were reduced by more than 90%.

Download and read the complete article telling what cause this resurgence and what options are available.

Tags: ,

Comments are closed.