SALEM — When it comes to fighting noxious and invasive weeds, both rural and urban communities share in the burden.

If left unchecked, weeds can destroy native habitat, clog waterways, damage recreational areas and reduce crop yields for farmers and ranchers. They can also tear up pavement, weaken building foundations and spread wildfire in bigger cities. 

According to a report issued by the Oregon Department of Agriculture in 2014, the state loses nearly $83.5 million in personal income each year from just 25 out of more than 150 weeds listed statewide. That’s equivalent to 1,900 private sector jobs.

“The effects just cascade,” said Troy Abercrombie, noxious weed program manager for ODA. “What you notice on the surface is often just the tip of the iceberg.” 

Abercrombie was hired in January to lead the program, replacing Tim Butler who retired after 44 years with the department. 

ODA’s noxious weed program is funded primarily through Oregon Lottery revenue, federal grants and cooperative agreements. Its budget was about $4.5 million for the 2021-23 biennium, Abercrombie said. He oversees five regional specialists covering the entire state, along with three administrative staff in Salem and two seasonal field technicians.

Together, they are the top line of defense against harmful weeds, collaborating with partners to keep the invaders at bay.

“We’re trying to protect our cultural, economic and agricultural resources,” Abercrombie said. “That drives everything we do.”  

How did they get here?

There are a myriad of ways that noxious weeds can be introduced, Abercrombie said. 

In many cases, they were used as ornamental plants in someone’s yard before escaping onto the landscape. Examples include oblong spurge — with its bright and attractive yellow flowers — and Japanese knotweed, which can grow in dense thickets up to 9 feet tall.

Other times, invasive species might be introduced at ports of entry, or simply hitchhike from one place to another in boat propellers, car tires or firewood.

Travelers can inadvertently bring noxious weeds home with them. Imagine, Abercrombie said, a tiny cheatgrass seed that gets stuck in a camper’s shoe or sock. 

“If that falls out somewhere … it only takes one,” he said. 

Apart from humans, there are plenty of natural pathways for weeds to travel. Seeds can be spread by wind or water, or even eaten and later pooped by migratory birds. 

“The list is endless,” Abercrombie said. 

What are the risks?

Once a weed becomes established, the consequences can be severe, be they economic, ecological, cultural or even threats to public safety.

Just two of the species studied in the 2014 ODA study — Scotch broom and Himalayan blackberry — were responsible for $79.6 million in economic losses. Both species are widely distributed across Western Oregon.

For example, if commercial timberland is infested with Scotch broom, then it could reduce the number of trees available for logging, Abercrombie said.

Or, if a 200-acre agricultural field is filled with 50 acres of weeds, that means fewer crops that can be harvested and sold. 

“If you have a landscape that a cattle rancher was going to graze, but it’s 70% covered in invasive annual grasses, now that rancher is going to have to supplement even more feed,” Abercrombie said. “It increases the operating costs of that rancher, because they have to transport hay out to those cows.” 

Weeds also pose a dilemma for the environment.

Abercrombie specifically mentioned flowering rush, an aquatic weed impacting the Columbia and Snake rivers.

The weed forms in dense mats, which slows down streamflows and builds up sediment. That, in turn, causes water temperatures to rise, creating habitat for another invasive fish species, northern pike, that preys on native salmon fry. 

Cities are not immune from the dangers, either. 

Abercrombie referenced a 1936 fire that devastated the coastal community of Bandon, fueled by an infestation of gorse, a highly flammable weed. 

Gorse remains widespread along the southern Oregon coast. 

“It’s a huge safety hazard,” Abercrombie said. 

How is the state fighting back?

ODA has three lists for classifying noxious weeds.

Weeds on the “A” list are extremely high priority, Abercrombie said. In some cases, they may not actually be present in Oregon or found only in a few areas, but the state wants to be proactive in preventing or minimizing their spread. 

“Anything on the ‘A’ list is targeted statewide for early detection, rapid response,” Abercrombie said. 

Flowering rush and giant hogweed are two examples of “A” list weeds. 

Then there is the “B” list, which includes weeds that are still problematic, but so widely abundant that they are not managed as intensively at the state level.

Scotch broom and Himalayan blackberry are both on the “B” list.

“If we went after all the blackberry, or all the ivy, or all the Scotch broom, we would never do anything else,” Abercrombie said.

Instead, ODA defers to partners, such as local soil and water conservation districts, to attack “B” list weeds. The state provides funding and technical assistance for specific projects through the Oregon State Weed Board Grant Program.

The program awarded $1.4 million in grants last cycle, Abercrombie said. 

Finally, there is the “T” list. These are weeds that have been targeted for eradication using biological controls — such as insects that naturally feed on the plant’s seeds or roots. 

Perhaps the most recognizable biocontrol is the cinnabar moth, used to control tansy ragwort.

Defining success can be a difficult proposition in the weed world, Abercrombie said. With limited resources, ODA must choose its battles smartly where they will have the most benefit. 

As budgets get tighter, Abercrombie said the state has and will continue to rely on landowners and SWCDs across the state to be their eyes and ears. 

“Some of the biggest discoveries of invasive species in the recent past came from your average civilian,” he said. “They do a great job, and that will continue to be the case.” 

George Plaven is a reporter for the Capital Press.