Diffuse Knapweed

Non-native species that thrive in new conditions typically become even stronger than their ancestors and that’s definitely true of diffuse knapweed. Despite only reproducing by seed and having a relatively short natural growing season, it has a weed super power that allows seeds to germinate if the plant is disturbed. That means any animal, strong wind, unusually heavy rain or interaction with a bike or motorized vehicle can initiate an extra growing season for diffuse knapweed which makes diffuse knapweed weed control very challenging.
Each mature plant can produce 18,000 seeds per year and has two natural growing seasons. Left undisturbed in a year with very little wind, diffuse knapweed can still drop up to 5,000 seeds through bud decay. As the buds weaken after they’ve served their purpose of attracting insects for pollination, seeds automatically drop.  Any remaining seeds left on the plant decompose and stay on the vegetation that also dies away.
But the very attribute that drew people to the American west – wide, open space – means there is plenty of wind to help distribute tumbleweeds full of seeds. And dried up diffuse knapweed becomes a rolling tumbleweed, sowing more seeds across the land it loves with every gust of wind.

Diffuse knapweed weed control options

Herbicide application is the most effective way of diffuse knapweed weed control. Since the plant greedily takes over land, planting and maintaining certain grasses can prevent new growth. In effect, the plant that crowds out other vegetation can be crowded out itself. Not every grass is suited for this elimination project. Check with a weed control specialist before planting to ensure the grass chosen won’t be harmed by future applications of herbicide (diffuse knapweed weed control treatment may take more than one growing season) and that you can adequately irrigate it to ensure vigor and strength.
Contact SprayTech, Colorado professional wee control specialists, at 720-248-0000 to discuss weed control options.