By Clarke McGrath

“Can you help us understand the label language regarding buffers and sensitive areas with these new dicamba herbicide products?” Extension specialists have fielded that question from quite a few farmers this winter and spring.

To help get this technology to the marketplace, EPA and the chemical companies included unique approaches to managing off-target movement in the label directions. Some of the language is a little vague, and several differences between XtendiMax/FeXapan and Engenia labels add to the confusion.

For example, applicators have to leave a 110-foot downwind buffer (or 220 feet at the higher rate of XtendiMax/FeXapan) between the sprayed edge of the field and neighboring sensitive areas, but the supplemental labels don’t clearly define "sensitive areas." North Carolina uses this language from the “master” label of Engenia to better define sensitive areas: “Residential areas, bodies of water, known habitat for threatened and endangered species, or dicamba-sensitive crop plants."

Buffers are a little murky, too. Listed areas include paved or gravel roads, unplanted agricultural fields, buildings or certain crops that tolerate dicamba, such as Xtend soybeans, Xtend cotton, corn, sorghum, millet and small grains. What about other potential buffers not specifically listed on the Section 3 labels — for example, ditches, roadsides, dirt roads, Conservation Reserve Program land or pastures? It’s a little complicated.

Master labels for the new dicambas list pasture, rangeland, CRP and farmstead (non-cropland) on the long list of approved crops or areas that can be treated with the products. But toward the front of these master labels, you can find language like this: “Avoid potential adverse effects to non-target areas by maintaining a setback between the application area and the closest downwind edge of sensitive terrestrial habitats (such as forested areas, grasslands, hedgerows, riparian areas, shelterbelts, shrub lands and woodlots) and sensitive crop plants.”

Some of this language isn’t new
That sounds incredibly restrictive, but some of this language isn’t new. Similar references to sensitive areas and endangered species can be found in generic dicamba labels.

Some sources say if you scout these ambiguous buffer areas and document they are free of sensitive or endangered species, you can use them. Others say, “If an area isn’t specifically listed as a buffer on the label, you probably don’t want to count it as part of a buffer.” Given the way the labels read, they are both probably right.

The labels do make it pretty clear that it is the applicator’s responsibility to determine the presence of any sensitive plants and endangered species in the vicinity (and follow all label restrictions to minimize the risk of off-target movement). So if you are looking at a potential buffer area, be sure to scout and document everything really well. Good communications with neighbors will be critical. Finding out what sensitive or specialty crops (including non-DT soybeans) and ornamentals they may have, and discussing your strategies for keeping dicamba away from them, could go a long way toward a safe and successful spray season.

With all that murky label language in mind, there is one thing that’s crystal clear: Nowhere does it say you have to use dicamba on Xtend beans. If it isn’t a great fit for a particular field, luckily there are still other herbicide options.

McGrath is the On-Farm Research and Extension coordinator for the Iowa Soybean Research Center at Iowa State University.