It sounds like something out of an old-time Western movie. The driving wind blows a tumbleweed across lonely Colorado highway and into a neighboring field.
Chasing tumbleweeds in Colorado
In the movies, these scenes portray a sense of inaction. The rolling tumbleweed is the only thing happening out there on the high plains. But in reality, tumbleweeds, known as kochia (pronounced KOH-sha), present a major challenge to growing a good crop. Fourth-generation grower Alex Rock knows this all too well. He and his family grow wheat, corn, soybeans, alfalfa, sunflowers and millet, some of which they feed directly to the farm’s herd of dairy replacement heifers and beef cattle. With so much going on, it’s the tumbling kochia weed that keeps Alex on his toes.
“Kochia will grow just about anywhere, in ditches, along fencelines, underneath your house and, of course, right through the middle of a cornfield,” he tells me. “It is a strange thing to look across a field in the spring and see a curved line of weeds. You know right away that a big kochia weed tumbled through the previous fall.”
A few details about kochia: it is not native to North America but was rather introduced as an ornamental plant for gardens around 1900. It is prized for its ability to grow in poor soils as well as its habit of changing colors throughout the growing season.
Kochia plants start out light green in color, eventually turning dark green and then deep red as they mature. A single plant can grow up to seven feet tall (over two meters) and spread nearly 50,000 seeds for many miles. With its low water requirements and overall robustness, kochia can also be grown as a forage crop in more arid areas. In short, what makes kochia a great garden plant or forage crop also allows it to seriously disrupt corn and wheat fields.
When it comes to managing kochia on his farm, the last three years have been particularly challenging for Alex. “We’ve had some pretty dry years. That gives kochia a natural advantage over our crops. We’re also seeing more and more types that are resistant to certain herbicides. We have to do some pretty extensive field scouting just to make sure that kochia doesn’t take over a field, and then all of a sudden we’ve lost a crop,” he continues.
So what else does Alex do to ensure that the tumbleweeds of the old Western films don’t turn into a modern horror movie? Alex emphasizes the need to rotate crops, which allows him to mix up his weed management programs and options. Depending on a field’s soil quality and water availability, Alex uses a 3 or 4-year crop rotation program, starting with wheat, then corn, millet, and finally fallow before going back into wheat. He’ll also use different herbicides, with a particular focus on changing up the sites of action, which refers to how and where a herbicide affects a specific weed.
“Mother Nature is always changing on us, giving us surprises, so we have to plan as best we can but also be ready to adapt at a moment’s notice. You never quite know which way the wind will blow. We wind up chasing kochia weeds from West to East, North to South and even sometimes East to West,” he says with a laugh. I’m a little shocked. Where I come from in the American Midwest, the wind only blows East to West when there’s a tornado. “I guess that is what makes farming fun though. There’s always a new challenge. I mean, the wind can literally blow backward.” Tumbling tumbleweeds indeed.