A Short Note on Kochia Control from the 2023 Season
By Mitchell Japp, MSc, PAg
Summary: This spring, I received a call from a barley farmer wondering what herbicide to use to control kochia in barley. We reviewed information on kochia herbicide resistance and recommended a new product with active ingredients from groups without known resistance. The grower reported back at the end of the season that the product was effective and resulted in a very low kochia population.
Problem: In early June, I received a call from a concerned farmer seeking advice on what herbicide would be suitable for controlling kochia in barley. Unfortunately, the in-crop spraying window was quickly approaching; and there were no records of herbicide resistance testing from this field. The kochia population has widespread resistance to Group 2 and Group 9 herbicides, but there was no data on Groups 4 or 14 resistance (although Group 14 is not suitable for in-crop use anyway). There was no opportunity to implement integrated weed management strategies at this time of the year.
Recommendation and outcome: Upon reviewing options for kochia control in barley, I investigated a new product called On-Deck, which includes Group 27 (active ingredient: tolpyralate) and Group 6 (active ingredient: bromoxynil) herbicides. The introduction of new mode of action (Group 27) provides additional control opportunities for kochia with resistance to multiple modes of action. The farmer decided to test the new product.
I was pleased to receive an update this fall regarding results from the On-Deck application. The field, which is saline and has a history of kochia problems, was nearly kochia-free this summer.
Gaining advantage: Implementing a viable herbicide program, combined with an integrated weed management plan, may effectively address kochia. Kochia seeds are short-lived in the environment, so back-to-back years with good control can dramatically reduce the viable seedbank for kochia. Combining an in-crop herbicide program with post-season and pre-season control options, increased seeding rates and other practices, including integrating livestock, are effective strategies. These strategies collectively increase crop competitiveness and reduce seed production, providing effective management of problematic weeds.