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Nevertheless, Lane adds, in one way, Sea-stedt's bugs have worked too well. Not only have they ravaged the knapweed, but they've also infested an area that was previously bug-free. "That's unfortunate," Lane says. "We don't have something to objectively compare it to."
Cindy Owsley, Boulder County weed-management coordinator, remembers when four species of knapweed-eating insects were released on a particularly sensitive acre of Walker Ranch back in the '80s. Ten years later, that one acre had become a hundred infested acres. "Now we have a significant problem," Owsley says. "And as a result, we have to use more herbicide."
Eight years ago, Owsley used bugs to control musk thistle. Although the bugs worked, they worked slowly, she says. When landowners gazed out their windows at what appeared to be healthy weeds, they complained -- and when she asked them to be patient, they complained even louder.
"I've been the subject of ridicule in that area ever since," she says. "If people look outside and see diffuse knapweed growing, and we say we're controlling it with insects only, it's going to be the same scenario. That's intolerable from a neighboring landowner's perspective. We feel a strong responsibility to be good neighbors."
According to Ron Stewart, a Boulder County commissioner, the commissioners support Seastedt's efforts. That's why they loaned him the 157 acres in the first place. But weed managers do not have the luxury of waiting five years for insects to become established, he says; the county cannot risk losing more land to diffuse knapweed. Which is why insects will probably continue to be "one more tool in the tool box" alongside herbicides.
"I've looked at his site. I've looked at the site where we have sprayed. And there's a lot less knapweed on the area we sprayed," Stewart says. "His project, to this point at least, does not prove you can do weed control without using multiple tools. We believe biocontrols have a very significant place in weed management, but I don't think he has proven that he can do it yet without the use of herbicides. "
Seastedt has heard that criticism before.
He welcomes it.
"Hey," he says, "I live and die on data. If I had failed with this, I was prepared to tell the world. But so far, it looks pretty good."
Seastedt realizes that insects alone will not stop diffuse knapweed, and he knows bugs do not work in all circumstances and in all conditions, including alongside roadways. But if used with other methods, such as hand-pulling or mowing, insects can keep the weed in check -- and with less damage to the environment and the pocketbook.
"For this species, I'm completely convinced that insects are less risky than chemicals," he says.
After four years, Seastedt's getting closer to the answer. And with weed warriors having fought the knapweed war for so long, that's "major good news," he says. "We've tried something that had been out there but not been tried in this way before. So far, we've potentially been lucky."
Seastedt doesn't worry that the imported beetles, weevils and flies will devour other plants. The feeding and reproductive habits of the five bugs are tied to the unique characteristics of knapweed, he says. But just in case, his researchers are keeping a close eye on the bugs. They've even sprayed knapweed juice on other plants to entice them.
"So far, the bugs are behaving themselves," Seastedt says. "I suppose anything is possible. Mutation happens. But there are 5,000 native insects that have the same potential to mutate. All we're doing is adding four more species that may do something weird, like suddenly decide to eat asphalt, but that's such a low probability that I don't think it's much of a risk. All these guys will probably do is go in search of diffuse knapweed until they die trying to find it. The worst-case scenario is that they'll munch on some distant relative of knapweed, like an aster. Anything beyond that is pure science fiction."
No matter how successful his experiments, Seastedt doesn't believe diffuse knapweed will ever be completely eradicated. In fact, he doesn't think weed managers should even try. At best, they can only hope to reduce the weed to a level that allows native plants and grasses to return.
"What I'd like to see is a prairie dominated by the vegetation we want to be there: native plants given the maximum potential to express diversity," Seastedt says. "If that means 1 or 2 percent cover by diffuse knapweed, that wouldn't bother me at all. It would be just like the dandelion. And if we can get knapweed to be like a dandelion, then we've done our job."