Off-label application can do more harm than good, industry experts say

A neighbor says when applying a certain herbicide or pesticide he gets the added bonus of additional benefits. Does this mean I should do it too?

The question can be complex. Those who work with the herbicides and pesticides understand why there is pressure to stretch treatment dollars. Still, going off label can be troublesome, too.

Ryan Bryant-Schlobohm, technical service manager for the south and central regions with UPL, stresses that producers need to follow the label regardless of what brand they use, and they need to know what results to expect. That means understanding the formulation in that product.

“The information is a foundation and that is what is going to guide you on how you want to incorporate this product and how you are going to incorporate it with other products and how to use all of the products in an efficient manner that will optimize your performance,” Bryant-Schlobohm said.

When he looks at a label he wants to understand what is in the formulation and what is it most effective against the insect or disease pressure.

“We want to know what pest we are targeting and if that pest is on the label,” he said, “and does it have enough activity to meet our satisfaction and what we are hoping to achieve.”

Products, for many herbicides, can be deployed with pre-emergence and others are designed for better efficacy post-emergence treatment. “We want to know if for a particular weed species what treatment works best.”

A company representative or Extension specialist can help answer questions, too, Bryant-Schlobohm said.

Fungicides may also be time sensitive meaning they may have a short window of time when they are most effective is another aspect to having an optimum treatment program, he said.

“A lot of our fungicides, for example, they are going to do very well before you even see a lot of disease development,” he said.

Some products are designed to have a more preventive mode of action, he said. For example on weeds, after emergence, the growth can be so fast that treatment cannot stay up with the growth.

“Know what pest you are targeting, know the product you are using and use it at the right time,” he said.

Nothing can be more disappointing to a grower than to have a promising crop derailed by weed or insect pressure that was not treated effectively, he said, plus with higher than normal per bushel prices for wheat, corn, sorghum and soybeans it is even more costly to lose valuable bushels this year.

Application rates are not a suggestion, either, he said. Most labels will have an application range to give growers discretion but he strongly suggests they stay within those rates.

Trying to stretch dollars by cutting the application can also cause problems, not only with a less effective kill rate but in the case of weeds it can actually increase the potential for herbicide resistance, which a grower wants to avoid, Bryant-Schlobohm said.

“Best use practices will intertwine with resistance management and the labels will have a big implication on a resistance management program when we follow the labels and follow the guidelines that is going to ensure we not only optimize the product and its performance and ultimately optimizing the lifespan of that product where we are putting off resistance development for as long as we can.”

Another reason to follow labels is that cropping practices might change for a particular year. Some of those common practices include double cropping such as planting sorghum after wheat or a grower may see potential in growing another crop that might be more profitable. He said when a rotation change occurs a grower needs to check the labels for pesticides and herbicides and think ahead to the following year’s crop.

“What you spray this year might have an effect on what you can plant next year,” he said, adding it all boils down to understanding your product, its impact on the soil and what the grower wants to accomplish in the long term.

Pay attention to weed size

He also said growers and herbicide applicators need to pay attention to weed size, in particular pigweed and waterhemp. It only takes a few days for those weeds to proliferate. There are treatments that can be highly effective but require a grower and applicator to be ready to act, he said.

“They will have the most effect when the weed height is small,” he said, adding that 2 to 3 inches is one benchmark although there are some applications and some weeds the effectiveness can be very good up to 6 inches but after that it does not take long for the weed to muscle its way through at the expense of the crop.

Once again, following the label, this time noting the height recommendations is critical to efficacy, Bryant-Schlobohm said.

Even with pre-emergence programs there are time-sensitive modes of action to follow, too.

Pigweed is on the forefront of many producers’ minds including those who grow corn, soybeans or cotton. A strong pre-emergence plan and a strong post-emergent plan are strategies where producers can find success but both require diligence with labels, he said.

Soybeans, cotton have other needs

Soybeans, because of concerns about dicamba drift, have been at the forefront of crop practices, according to another expert. Cotton is another product.

“We live by the mantra ‘the label is the law’ and work hard to support the science-based risk standards under (Federal Insecticide, Fungicide and Rodenticide Act),” said Lee Van Wychen, executive director of science policy with the National and Regional Weed Science Societies, Alexandria, Virginia. FIFRA is a federal statute that governs the registration, distribution, sale and use of pesticides in the United States, according to the Environmental Protection Agency.

Van Wychen noted studies of dicamba-tolerant soybeans and cotton, in 2018 and 2019, respectively, at https://www.regulations.gov/document/EPA-HQ-OPP-2020-0492-0003.

Those studies indicated the numbers were higher and, because of restrictions, using off-label dicamba products has to be closely evaluated by growers.

Non-over-the-top dicamba products for cotton and soybean applied at planting, or after planting, are off label because of preplant restriction of a specified number of days and the amount of rainfall between dicamba application and planting to avoid crop injury from dicamba, Van Wychen said.

Dave Bergmeier can be reached at 620-227-1822 or [email protected].