Invasive Whitetop prospers in Malheur County

By Pat Caldwell

The Enterprise

VALE — Heavy winter snowfall and a wet spring spawned a bumper crop of weeds locally.

Whitetop especially thrived in the county during the spring and early summer, though the invasive weed has now mostly gone to seed.

“It forms these really dense stands and gets to be a real problem to control. It showed up in a lot of areas,” said Stuart Reitz, cropping systems agent for the Malheur County Experiment Station.

Gary Page, Malheur County weed inspector, said whitetop is a “bigger issue” every year.

“People haven’t taken it very seriously and it has gotten pretty much out of control. It does really well. It likes this climate and likes the soils,” said Page.

Page said the damp spring gave weeds like whitetop a head start.

Like other invasive weeds in the county, whitetop arrived uninvited and quickly put down roots.

“It is a thought to be an alpine plant from central Europe,” said Page.

Whitetop probably arrived in the county 30 or 40 years ago, Page said, either through contaminated seed or from livestock.

While some native weed species — such as cheatgrass – have dotted the local landscape for decades, most of the invasive weeds in the area are relative newcomers, said Page.

“By and large the weed issue has developed since the 1970s. They are expanding rapidly over the last decade probably because there is more human activity out here,” said Page.

Humans can unknowingly deliver weed seeds into the area through boats, RVs, ATVs or even on their boots and shoes. Once they arrive, weeds tend to quickly colonize native plants and win out for precious natural resources such as water.

“The county has been kind of remote from human traffic but that is changing. Lots of people are coming here and recreating here,” said Page.

That opens up more channels for invasive weeds to reach Malheur County.

There are several herbicides that can be used against whitetop, said Page.

“Things like Escort and Tellar are effective against whitetop. People do use Round Up but it is not the most effective and we don’t recommend it normally,” he said.

Weeds like whitetop are not just a nuisance. They are a direct threat to the local economy, said Page.

The livestock industry, the county’s largest economic engine, is particularly affected.

“The majority of livestock that get into the market in this county start on the rangeland. Cattle don’t like to graze whitetop. And their digestive systems do not tolerate it well,” said Page. “It is beginning to be a big problem on the ranges.”

Page said the appearance of whitetop on range land is a bit of a surprise.

“We used to think it would be contained to the riparian habitats. However we are starting to find it some really dry and remote areas,” said Page.

Page said he is not sure how the weed ended up on remote ranges but believes humans are the culprits.

Page said his department relies on federal grants through the U.S. Bureau of Land Management and the county’s general fund along with help from the Malheur County Cattlemen’s Association to pay for weed eradication.

Page said his department’s whitetop spraying operation is just a stopgap.

“What we sprayed, what we actually treated, is probably miniscule compared to the vast amount out there,” Page said.

Page said there are “hundreds of thousands” of acres of whitetop in the county. Page said his department sprayed 140 to 150 acres of whitetop in the county.

Page said the goal is to focus on key areas to eradicate the weed.

“Our goal is to work on the outbreaks or the outlaying areas or higher value areas where it doesn’t have a higher presence yet,” said Page.

The high-value areas, said Page, include sage grouse habit, forests, or places that contain threatened plants.

“Those are the things we are looking at and think we can have a positive impact on,” said Page.

Page’s department isn’t spraying for whitetop now and instead is tackling different invasive plants, such as skeletonweed.

Skeletonweed is a member of the daisy family and native to Europe, Asia and North Africa and is showing up in Malheur County.

“There are gobs and gobs of it in Ada County,” said Page.

Once again, he said, the plant arrives in the county via humans.

The use of herbicide on skeletonweed works after several applications.

Whitetop and skeletonweed are just two invasive species that create problem in the county. Cheatgrass, yellow flag iris along with yellow nutsedge impact different crops at different times of the year.

Yellow flag iris, Page said, can clog up waterways and alter flows while yellow nutsedge impacts onions and potatoes.

Other weeds that colonize portions of the county include: knapweed, leafy spurge, yellow starthistle and Japanese knotweed.

Those weeds are probably here to stay, Page said.

“You may be able to control one, but that is only one piece of it. So if you eliminate a weed there are a dozen other species that can fill the niche,” said Page.

Have a news tip? Contact reporter Pat Caldwell at [email protected] or (541) 473-3377.