Managing herbicide resistance costs

Farmers considering herbicide resistance strategies are looking at the economics first

Implementing strategies to stave off herbicide resistance can bring increased costs 
to individual farmers in the short term, while the economic benefits are delayed.

There are several reasons many farmers haven’t yet adopted herbicide resistance management (HRM) plans. These include a lack of information, the complexity of different management strategies and limited time. But a major reason is still economics. Many farmers worry about the costs of implementing a resistance management plan, especially if they’re uncertain about the potential benefits.

Managing herbicide resistance is a long-term problem. Farmers implementing strategies often face increased costs in the short term, due to more chemical inputs, higher equipment costs or more labour. The benefits — better product stewardship and more options for long-term effective weed control — are delayed.

“Two interrelated socioeconomic phenomena that create a barrier to HRM adoption for individual farmers are impatience and uncertainty,” says Dr. George Frisvold, agriculture and resource economics professor at the University of Arizona.

“HRM can lower returns today with more or less certainty while the benefits are in the future and more uncertain. So farmers are weighing certain, upfront costs against less certain future benefits,” says Frisvold.

Another economic reality is that North American farms are getting bigger, which has driven the need for intensive weed management systems that are less demanding of farmers’ time. “Going back to more diverse management systems is hard because time constraints are a bigger factor for managers on bigger operations,” says Frisvold. “There are also a lot of small, part-time farmers who get most of their income from off-farm jobs and businesses. For this group too, there is less time for management-intensive farming.”

Increasing herbicide resistance

Some farmers don’t adopt best herbicide stewardship practices because they are overly confident that the industry will develop new chemical solutions to herbicide resistance, which traditionally has been the case when resistance problems have arisen.

“Farmers with a greater degree of this confidence are less likely to adopt more diverse HRM strategies,” says Frisvold. “What is different now is that industry has not developed a new commercial herbicide mode of action in about 30 years. More and more weeds are evolving resistance to the existing modes of action (MOAs). Industry has and is developing herbicide tolerant crops that make the old MOAs more useful, but many weeds are already resistant to these older MOAs.

Research suggests that herbicide resistant weeds are more mobile than previously thought, and that seed and pollen can spread in a number of different ways, including by wind, water, animals, farm machinery and transporting crop residues off the field. “When weeds are mobile, individual growers cannot prevent their neighbours from increasing the population of resistant weeds, that then infest their own fields,” says Frisvold. “If growers think individual actions are pointless they won’t take them.”

The problem arises when everyone thinks this way. In some cases — where weeds aren’t mobile — growers do have control over resistance. “If weeds are mobile, through seed dispersal, moving with custom machinery, etc. group action might be needed,” says Frisvold. “Getting farmers to organize and impose controls on each other is difficult. That said, we have seen successful programs like Boll Weevil Eradication where they have done just that.”

The United States Department of Agriculture (USDA) began the Boll Weevil Eradication in the 1970s, using integrated pest management to help cotton farmers eradicate most of the boll weevil pests across the country. The program resulted in an overall reduction in pesticide use and increased yields. Proving the long-term value of co-ordinated strategies, the U.S. National Cotton Council says on its website, “The National Boll Weevil Eradication Program ranks close to Eli Whitney’s invention of the cotton gin as one of the greatest advancements ever for the U.S. cotton industry.”

What’s the bottom line?

Another big barrier to HRM is that farmers don’t have a true grasp of the economic implications of adopting HRM strategies on their specific farm and for their specific crops, because this kind of data is still not widely available in North America.

Frisvold suggests there are three possible scenarios for farmers adopting HRM plans. The optimistic case is that a farmer adopts HRM strategies and is more profitable in the short term as a result. “This scenario is a no brainer, it makes sense to be doing it now,” says Frisvold. “We need to identify these cases as much as possible, wherever they are, and this is where traditional demonstration, education and extension may suffice if we are able to communicate to growers that this makes sense for you today. But the results must be clear and convincing so they know that it makes economic sense.”

The intermediate case might mean farmers have to do things that reduce profits in the first few years but it only takes a few years after that to see a net gain from the HRM plan because the system is in place and they are preventing future resistance problems. “Simply providing information in this case may be insufficient because growers have to calculate how many years before it is going to pay for itself,” says Frisvold. “Growers with more short-term economic stress, higher discount rates or plans to sell for development may be less likely to adopt HRM, and economic incentives may be needed to encourage adoption for these farmers.”

The pessimistic case is one where the farm is less profitable for a large number of years or the benefits that farmers see are so far in the future they are discouraged from doing any HRM because they know it’s going to take too long to pay for itself. “In this case the messaging is the most difficult because the long time frame increases farmers’ uncertainty about achieving any benefits,” says Frisvold. “Additional economic incentives or cost sharing programs may be needed to encourage adoption.”

Multi-faceted approach needed

Many experts in the HRM field believe that governments need to provide short-term financial incentives or cost-shared programs to reduce the cost of developing and implementing field-by-field herbicide resistance management plans and encourage farmers who wouldn’t or couldn’t otherwise adopt them to do so.

Agricultural extension specialists, academics, agronomists, industry representatives and consultants all have a role to play in communicating the effect of HRM on short-term and long-term farm profitability once this information is available. “Farmers need to know what’s the bottom line, what is this going to do on a per acre basis over different states and different production systems,” says Frisvold, adding it’s not an easy thing to collect and analyze this kind of data. “You’ve heard the term, ‘This isn’t rocket science?’ Well, the math involved in solving these bio-economic models literally is rocket science — it uses the same type of math.”

The USDA, the Weed Science Society of America (WSSA) and others are working to come up with predictive economic models for herbicide resistance management implementation.

As an example the Weed Science Society of America (WSSA) conducted an economic model exercise that demonstrated the benefits of proactive HRM of horseweed. Depending on crop type and production system, the HRM could pay for itself in as little as two years and increase farmer profits 14 to 17 per cent over 20 years.

Researchers at the University of Arkansas and Texas A & M University are taking a slightly different approach, working on a palmer amaranth management (PAM) model, which is showing promise as a model for assessing the economics of other herbicide resistant weeds. This model should provide growers with a more usable, hands-on tool to consider different HRM options.

Community-based approach critical

Herbicide resistance isn’t going away any time soon, and it’s in the collective, long-term interest of all farmers and others involved in agriculture to delay resistance by implementing integrated weed management strategies. This includes biological controls such encouraging beneficial insects like crickets, which can reduce weed seed banks by eating weed seeds on the soil surface. This also includes mechanical solutions such as strategic tillage operations to meet the needs of a specific field or site, and cultural options such as crop rotations, cover crops, or adjusting seeding dates and row spacing.

But most important is the need for a community-based approach to weed management that recognizes herbicide resistance is a shared problem. The most effective weed management programs will be those developed and led by farmers themselves, in collaboration with industry, governments and university researchers, and which are localized to meet site specific weed management needs.

About the author


Angela Lovell

Angela Lovell is a freelance writer based in Manitou, Manitoba. Visit her website at or follow her on Twitter @angelalovell10.



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