An invasive plant well known in western Oregon and the Pacific Northwest has been spreading in Umatilla County.
Umatilla County Weed Control Supervisor Dan Durfey said garlic mustard made its first appearance in eastern Oregon atop Cabbage Hill several years ago and has since traveled down drainages to the Umatilla River all the way to the Oxbow site in Hermiston.
He said the weed will eliminate small native plants and “take over everything” in areas under trees, where the plant thrives. While Durfey is most concerned with preventing garlic mustard from spreading into the timber from Cabbage Hill, he said people should be aware of the high-priority invasive species as it continues to spread down the Umatilla River and inform the county weed control department when it is found.
“As long as we know where it is, and people know about it, that’s half the battle right there,” he said. “When we know where it’s at, if it’s expanded like this stuff has, we can make a better game plan on containing it.”
He said garlic mustard is a cool-season herb native to Eurasia that few animals will eat because of its distinct smell.
“It’s pretty easy to identify,” he said. “All you’ve got to do is grab a leaf and squish it between your fingers, and then you can smell it really easily. The leaves produce a distinct garlic odor when crushed.”
The plant has white flowers in April or May, Durfey said, but does not bloom for very long before going into seed production. He said the weed, with its “kidney-shaped leaves,” can be difficult to spot because it blends in with other plants in wetter areas next to trees.
“The plant height is supposed to be 12 to 48 inches, although, I’ve seen some where the plant leaves are as big as my ball cap, and there are plants along the Umatilla River as tall as I am,” he said.
Durfey said the Oregon Weed Board aggressively targets garlic mustard, and he has received two grants to address the only known outbreak in eastern Oregon. Although the herbicides registered to kill garlic mustard are not extremely effective, he said he tries to “stay on top of it” with spring and fall applications.
Durfey said he is currently focusing on the areas upriver to prevent reseeding downriver and will eventually progress downward to sites such as Oxbow, but the plant will continue to spread.
The weed can be pulled by hand, he said, but the plants should be placed in bags immediately and burned because their high-water content allows them to “go to seed” the same day.
“If you hand pull it and just stay after it, you can control it that way,” he said. “Being mustard, it produces a lot of seeds, so it takes a lot of effort to take care of it.”
Durfey said he hopes people will learn about garlic mustard and other invasive species to help prevent further spread.
“The only good thing about having it at Oxbow is it’s a high-traffic area, and it’s a good opportunity to educate (people) about the weed and any noxious weeds,” he said. “The best way to take care of it is through more education. The more eyes on it, the more it helps us.”
People can contact Durfey at 541-278-5462 or firstname.lastname@example.org.