Battling invasive weeds - A call to action for farmers

By Scout Nelson

The agricultural community is facing a growing challenge with the spread of invasive weeds such as kochia and Palmer amaranth across regions, including North Dakota and Minnesota.

Quincy Law, an NDSU assistant professor and expert in invasive weeds, underscores the urgency of addressing herbicide resistance in these species, particularly kochia, which has developed resistance to key herbicides used in burndown strategies.

The discovery of PPO-inhibiting resistance in kochia to common herbicides like carfentrazone and saflufenacil has narrowed the options for effective control to alternatives such as paraquat.

This development calls for a reevaluation of herbicide strategies among producers, especially as these resistant populations are not confined to one area but have been identified from Minot to Mott, N.D., and beyond.

The situation is further complicated by the presence of highly competitive weeds like Palmer amaranth, which not only grows rapidly but also exhibits a wide window of emergence, making it difficult to manage with pre-emergent herbicides alone.

The weed's ability to produce up to a million seeds per plant, coupled with its significant resistance to multiple herbicide action sites, highlights the need for a diversified approach to weed control.

NDSU's ongoing research, supported by various agricultural councils, aims to quantify the yield impact of these invasive species and explore effective management strategies.

Preliminary findings indicate substantial yield losses in soybeans and corn when competing with Palmer amaranth, even with early planting and pre-emergent application.

To tackle the spread and impact of these resistant weeds, experts recommend a combination of pre-emergent herbicides and follow-up post-emergent control, utilizing multiple sites of action to tackle the problem from different angles.

This approach is critical in managing existing infestations and preventing the further spread of these invasive species through contaminated machinery or feed.

The state's response, including NDSU's establishment of a research site specifically for Palmer amaranth, signifies the gravity of the issue and the concerted effort required to manage these invasive weeds. 

With confirmed cases of Palmer amaranth in 19 counties, the agricultural community is urged to remain careful, adopting comprehensive weed control strategies to protect crop yields and prevent further spread.

This challenge underscores the importance of collaboration and innovation in agricultural practices, ensuring the sustainability and productivity of the region's farming operations in the face of evolving threats.

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