Protect land values with weed management

OGLESBY, Ill. — It’s common knowledge that weeds impact cash crop yields, but they can also impact farmland values.

“Unfortunately, there’s not a lot of hard and fast data that’s out about the direct impact of weeds on land values. So, we have to think of this more indirectly,” said Kathryn Seebruck, University of Illinois Extension commercial agriculture educator for agronomy and crop sciences serving Jo Daviess, Stephenson and Winnebago counties.

Seebruck was among the presenters during the U of I Extension’s Farmland Owners Conference at Illinois Valley Community College.

She referred to an ag lender’s quote in the late 1990s on the weeds versus land values issue: “The basic value of any income-producing investment is based on the projected income flow the investment will produce.”

“So, if your income-producing investment is land and that land is not producing, you’re not getting as much income flow from that — that land value is then decreasing,” Seebruck said.

“Weeds are going to do a pretty good job of degrading that land value when left uncontrolled or at least improperly managed.”

A survey and case study brings to light the correlation between land values and weeds. Syngenta conducted a study in 2010.

Farmers were surveyed one year and those same farmers were surveyed a few years later to see how their answers changed over time.

Overall, the survey found that the impact of weed resistance on land values increased over time.

The study stated that the cost to manage glyphosate-resistant weeds increased to $16.90 per acre in 2010. The estimated yield loss associated with glyphosate-resistant weeds was 5.5%.

The resurvey found that the perceived impact of weed control practices on rental and appraisal values increased to 22%.

“That study was in 2010, so, in all reality, these numbers are likely much higher today. Also, this only looked at the glyphosate-resistant piece because back then that was kind of the hot super-weed issue at the time, but now we have multiple resistant weeds,” Seebruck said.

“Now we can kind of assume that these numbers are much higher, based on today’s situation.”

Ranch Devalued

A case study in invasive weeds that, if uncontrolled, can seriously degrade land values was released in 1992, focusing a leafy spurge infestation from the 1960s through the 1990s in North Dakota.

“In 1975, only a few year after the leafy spurge infestation had started and it wasn’t nearly as bad as it would get, two brothers purchased a ranch near Brooks Ranch at full market value,” Seebruck said.

“In three years, they deeded most of that land back to Farm Credit Services because the leafy spurge infestation was such an issue for them. They had livestock and leafy spurge was taking over pastureland. Their forage production wasn’t meeting their needs, so they deeded it back.

“It took Farm Credit Services over 15 years to be able to resell that land because of that leafy spurge infestation.

“The pasture should have sold for $100 to $125 per acre back then. The price then dropped to $40 an acre by the time they were able to sell it 15 plus years later, because by the time they sold it, it was 100% covered by leafy spurge.”

Competition

In the agricultural setting, weeds that typically infect farmland have very specific traits that make them hypercompetitive against cash crops.

“They’re extremely opportunistic. There’s a quote that I really love, ‘nature abhors a vacuum,’ and weeds are kind of the epitome of this. If you’ve ever seen a bare patch of soil, whether it’s in your yard or a fallow field before planting has occurred, it doesn’t stay like that for very long,” Seebruck said.

The second trait that makes weeds so competitive is their adaptability, which Seebruck said was the most important and significant trait.

“They don’t just adapt to their environment, but they adapt to the mechanisms of control that we inflict upon them — most notably, our herbicide applications. Herbicide resistance is the quintessential example of how weeds adapt to control measures that they are subject to,” she said.

The Herbicide Resistance Database states there are 533 unique documented cases of herbicide resistant weeds globally. The “unique” case is defined as a specific species being resistant to a specific site-of-action of a herbicide.

The United States has 131 unique cases of documented herbicide resistant weeds, and Illinois has 29 documented cases of herbicide resistance in specific species.

“In Illinois, we have a documented case of waterhemp that is resistant to six different herbicide sites of action and that is very significant because that’s six less options that unfortunate farmer has at controlling that population,” Seebruck said.

The third most important trait that makes weeds so competitive is they are extremely prolific seed producers, especially those weeds you typically find in an agricultural production system.

They can produce thousands upon thousands of seeds on a single plant, thus contributing to the soil seed bank.

A 2016 study looked at corn yields in different weed management practices — in one treatment, all of the recommended best management practices, including a herbicide program to control weeds.

Another treatment included all of the best management practices used to grow corn, but without weed management.

The trials determined that without any weed management practices being implemented, the corn yield was reduced specifically only from weed interference by 50%.

No Single Solution

“There’s never going to be a single mechanism of control that’s going to solve all of our problems and there certainly isn’t going to be a single new product that comes out that’s going to solve all of our problems,” Seebruck said.

“Herbicide discovery takes a lot of time, it takes a lot of money, there’s a lot of regulations. Getting a new herbicide product to market is very difficult. If you’re waiting around for that silver bullet product that may or may not come out, you sure as heck better be doing something in the meantime to control those weeds.”

Don’t rely solely on chemical control to begin with.

“Even if we did get that miracle product, we’re going to overuse it and then we’ll be right back to square one. We’re going to have resistance and then we’re going to be waiting again for another new product,” Seebruck said.

“We really shouldn’t rely on any other single form of control, either. These weeds are extremely adaptable. It’s not just herbicides they adapt to and evolve resistance to.

“They also adapt to planting dates. Up in northern Illinois, giant ragweed over time has shifted its emergence pattern to emerge later in the spring to avoid being hit by early herbicide applications.

“That’s not necessarily a true form of herbicide resistance, but it’s a really good example of how adaptive they are.

“We should be diversifying our weed control. This is our best bet against resistance evolution, effectively controlling weeds, making sure we’re limiting the spread of any noxious or invasive weeds.”

Multiple Controls

To best control the problem and maintain farmland values is to implement an integrated weed management system that includes using many other control measures first before applying herbicides.

“You are going to implement multiple methods of control. It can be a number of things. It can be a different combination of things. There’s not a one-size-fits-all approach. It depends a lot on your operation, your preferences, your finances, but herbicides should be your last resort,” Seebruck said.

“Cover crops have been touted more for their soil health benefits, but they do have weed control benefits, too. Cultivation can be used if you’re not necessarily worried about conservation.

“Diversified cropping rotations can help break up the weed’s life cycle which makes them easier to control with other methods.

“If you do resort to using herbicides, we’re never going to get to a point probably where no one needs a herbicide, but if we do use them, we just want to make sure we’re using them appropriately.

“Rotating or mixing modes of action together in the same application is your best bet against mitigating the likelihood of resistance from evolving in a population.”

Seed Bank

Seebruck encourages farmers to not let weeds go to seed.

“I know it sounds really, really hard, it sounds impossible, but if we implement many measures of control, we’re diligent and scout to make sure our control measures have been effective, this more possible than it might seem,” she said.

“This should be our ultimate goal because it’s the ultimate defense against resistance evolution, reduces the soil seed bank and helps prevent the spread of invasive and noxious weeds.

“Weeds have specific characteristics that make them so hyper competitive, at least in crop production systems. That competitiveness can then lead to very serious adverse effects on our crop production which then can reduce our land values.

“At the end of the day, a solid integrated weed management strategy helps mitigate herbicide resistance evolution, reduces the soil seed bank, prevents the spread of noxious, evasive and super weeds, which all together doing these things help to protect our crop yields and then ultimately protect your investment as landowners.”