Weeds like Palmer amaranth, waterhemp, kochia, and marestail are escalating challenges for High Plains farmers growing corn, soybeans, wheat, and sorghum.
Arkansas, Colorado, Iowa, Kansas, Missouri, Montana, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming growers are fighting herbicide-resistant weeds and rising input costs have been inflating production expenses, threatening yields and squeezing margins. This column examines weed trends, economic impacts, and yield developments, with a detailed cost breakdown from the U.S. Department of Agriculture and Kansas State University.
Trends in weed challenges
Herbicide resistance dominates weed management in the High Plains. In Iowa and Nebraska, waterhemp resists glyphosate, Acetolactate Synthase Inhibitors or ALS inhibitors, and Protoporphyrinogen Oxidase Inhibitors or PPO inhibitors, while kochia in Kansas and Oklahoma evades dicamba.
Wetter springs in Missouri and Arkansas extend weed germination, and drought-tolerant Russian thistle thrives in Texas and New Mexico.
Integrated weed management is gaining traction. For example, cover crop adoption in South Dakota has increased. Precision sprayers are showing promise, as seen in trials saving up to 76% on herbicide use in some U.S. corn and soybean fields. IWM uses multiple control features including mechanical, cultural, biological, and chemicals to control and prevent weeds.
However, adoption lags in Wyoming and New Mexico due to cost and ability barriers.
Economic considerations and cost breakdowns
Weed control is a major expense, with chemical costs (herbicides, insecticides and fungicides) forming 7% to 22% of total operating production costs, depending on the crop, based on USDA-Economic Research Service data as shown in Figure 1.
Historically chemicals used for corn production had the lowest share of total operation production costs, but increased during and through COVID-19. Chemical costs for sorghum have the highest share at more than 20% of total operating production costs compared to corn, soybeans and wheat.
Herbicide expenses have risen 15% to 20% as farmers use multiple modes of action. Treating crops for weeds is important. For example, a single Palmer amaranth plant can cut sorghum yields by 30%, costing $50 to $100 per acre at current prices.
Since 2020 chemical costs for corn production more than doubled from about $30 per acre across the High Plains, peaking at nearly $65 in 2022 before retreating to $53 in 2024. Chemical costs were higher due to supply chain disruptions, higher material, handling, and packing costs.
Chemical costs for sorghum and soybeans increased from about $30 per acre in 2021 to $45 in 2022 and settled at about $37 in 2024.
Chemical costs for wheat are historically lower than the other crops, but did increase in comparable manner from $15 per acre in 2021 to $20 in 2022 and 2023 and $17 in 2024. The cost of chemicals across the High Plains is shown in Figure 2 by crop.
For corn, it was estimated by researchers at K-State in their farm management guides for 2025 that herbicide costs range from a low of $55.84 per acre in southeast Kansas to $115.48 per acre in the Southwest region. These herbicide costs would essentially exceed the average chemical cost across the High Plains and reflect higher operating costs in Kansas overall.
Soybeans and sorghum follow similar patterns, while wheat’s lower costs reflect less intensive programs. Non-chemical costs, like hand-weeding ($20 to $50 per acre for soybeans) or cover crops ($30 to $60 per acre in Montana), add to the burden. Precision technologies ($10,000 to $50,000 for sprayers) remain inaccessible for smaller farms in Oklahoma or New Mexico.
Yield implications
Weeds reduce yields significantly. In 2023, U.S. corn production fell 13% to 14.2 billion bushels, with weeds contributing to losses in Iowa, despite yields of 185 bushels per acre.
Soybeans averaged 52.5 bushels per acre, but Arkansas’ losses reached 10% due to weeds.
Wheat production rose 9% to 1.98 billion bushels, but kochia cut Kansas yields by 15% where it was an infestation.
Sorghum in Texas (50 to 60 bushels per acre) faces 10% to 30% losses due to weed infestations.
IWM, like Nebraska’s pre-emergence herbicides, sustains corn yields above 180 bushels per acre, but uneven adoption limits gains.
Weed management strategies
Effective weed management varies by crop and region. For corn, K-State recommends pre-emergence herbicides (e.g., atrazine) followed by post-emergence glyphosate or dicamba in resistant areas, with total herbicide treatment costing $55.84 to $115.48 per acre.
Soybeans receive help from narrow-row planting and residual herbicides like metolachlor, reducing waterhemp by 15% (Iowa State University Extension, 2023).
Wheat relies on fall-applied 2,4-D or dicamba for kochia control, with cover crops boosting yields by 5% to 10% in South Dakota (South Dakota State University Extension, 2024).
Sorghum in Texas uses spot-spraying for Palmer amaranth, with IWM cutting losses by 10% to 20% (Texas A&M AgriLife Extension, 2024).
Adoption of these strategies is still inconsistent due to economic constraints.
Regional and policy considerations
Weed pressures vary: Iowa’s humidity demands early soybean herbicide applications, while Texas’s arid conditions favor spot-spraying.
Kansas and Nebraska benefit from K-State and University of Nebraska Lincoln’s research, but smaller farms in Wyoming lack access. Subsidies for cover crops or precision tools could reduce herbicide reliance, addressing economic disparities.
Conclusion
High Plains farmers face rising weed control costs ($26 to $115.48 per acre for corn depending on the region) and yield losses. K-State’s data underscores regional challenges, while IWM offers hope if supported by policy to ensure affordability and equity.
Ken Eriksen can be reached at [email protected].
