Kochia is known for being an aggressive, adaptive weed. This year showed some farmers just how tenacious this species is. At spray timing, at harvest, and even after, kochia is a constant issue, and it’s not going away any time soon.
Jason Lindgren, with NuFarm Canada, says that lighter competition this year due to dry conditions really showed off how that aggressive growth kochia is known for and how multi-flushes all year can wreak havoc on fields.
Lindgren says that the one-pronged approach — depending on a herbicide — just isn’t enough to get a handle on this weed. “It’s not successful,” Lindgren says. “It’s prolific, and gets around herbicides.”
Herbicides are definitely a huge means of control, but it’s the details and the layers of control that are necessary for kochia control. The layers come in several forms: from ensuring water quality for herbicide application efficacy, to optimal speed and water volume for ideal coverage, and thinking about control at pre-seeding, in-crop, and post-harvest.
What’s more, Lindgren says, you’ve got to add in a second effective mode of action. “You’ve got to kill it twice,” he says. Keep in mind, there are confirmed Group 2,9, and 4 resistant biotypes out there.
Chem fallow is also a major cause of HR kochia, therefore DON'T FALLOW!
— Clark Brenzil, PAg. (@SKweedgeek) November 8, 2018
It’s also time for farmers to think about the possibility of taking corners or areas of fields out of production. Saline areas or those areas that you’re always fighting with to get a decent crop to grow become seed-producing reserves for kochia, Lindgren says. Because of its tumbleweed nature, those pockets of plants continue the weed’s spread even when you’ve managed good control in the rest of the crop. Seed those areas to grass instead.
What can you do if you suspect you’ve got herbicide resistant kochia? There is some testing available through Agriculture and Agri-Food Canada, so get a sample (a mature plant, please), and send it in so you at least know what you’re dealing with.