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Grass weed spreading throughout PNW

Field tours offer ventenata tips

By Matthew Weaver

Capital Press

Published on August 21, 2013 9:35AM

University of Idaho researchers are holding field tours to give farmers the latest information on ventenata, a grass weed that is increasing throughout the Northwest.

The university field tours to discuss ventenata management begin at 1 p.m. June 13 in Usk, Wash., and 8 a.m. June 19 in Moscow, Idaho.

Ventenata is a relatively new weed, a winter annual grass that germinates in the fall and produces a seed head in the spring.

"I don't think we've seen the full extent of its impact yet," said Tim Prather, UI weed ecology professor. The weed is found in virtually all eastern Oregon and western Idaho counties and many Washington counties, and it continues to expand.

Hay farmers are reporting reduced yields, decrease in stand life from 10 years to five years and ineligiblity for the export market.

Prather estimates ventenata can drop hay from a value of $220 per ton to $70 per ton.

"That's a pretty drastic loss," he said.

Farmers who don't yet have ventenata will want to watch their roadsides against a county road or a highway, Prather said. It also shows up first on roads within a farm operation.

Prather said the field tour agenda includes results from a survey of 500 forage producers and some herbicide screening work. Researchers will be collecting information this summer from experiments begun last fall in land in pasture, range, hay production and the USDA's Conservation Reserve Program.

The researchers have developed plans for treatment on range conditions, including whether herbicide treatments also impact desirable forage crops. Some herbicides would be useful in pasture and range systems that are grazed, including Monsanto's Outrider herbicide in the fall or Plateau herbicide in some cases of CRP land.

Healthy pasture grasses will also be helpful. In hay, researchers are recommending timothy hay not be grazed after the last harvest. Higher cutting heights make for more robust grasses, Prather said. Researchers are working to register a herbicide for timothy hay, but there's no firm answer yet, Prather said.

"One of my goals is for those counties where it's just an emerging problem, my hope is they don't wait until it becomes a big problem," Prather said. "That's a common problem, that we don't get at it early enough. There's a lot of counties that potentially could be affected that are just now hearing about it. They should be really concerned rather than wait and see if it develops into a problem."

Ventenata can also potentially create challenges for wildlife, he added, noting it has affected nesting birds and insect diversity on CRP land.

"We're not done being worried about the impact of ventenata," Prather said. "We've got a lot of questions still to answer."

Prather asks farmers to RSVP for the Moscow, Idaho event, which will include buses. Call 208-885-9246 for more information.


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