Dozens of pesticide applicators gathered on Feb. 7 at a hotel conference room in Champaign, Illinois, for an hour-long training now required to use three products that contain formulations of the weed killer dicamba.

The new training requirement this year resulted from widespread complaints from farmers and applicators that the products, developed by agriculture companies Monsanto and BASF, had the ability to move off-target and cause damage to non-dicamba resistant plants, even when applied according to the directions on the product labels.

Those complaints to agriculture departments across the Midwest and South prompted the U.S. Environmental Protection Agency in October 2017 to make the products “restricted use,” meaning they can only be applied or purchased by a licensed applicator. Many states announced additional restrictions as well.

The EPA also updated the labels on the three products – Monsanto’s Xtendimax, DuPont’s FeXapan and BASF’s Engenia – to include an annual training specific to dicamba or its family of chemical herbicides.

The Feb. 7 training at the I Hotel and Conference Center, offered by the Illinois Fertilizer & Chemical Association, focused on some of the changes to the label meant to prevent the ambiguities and off-target movement that occurred last spray season, and that led some states like Arkansas and Missouri to go as far as a ban on dicamba during certain months.

One major change to the label is a restriction on the time of day when dicamba can be applied.

This season, spray can only occur between sunrise and sunset, when the product is less prone to volatilize and move on to neighboring fields. Monsanto has said that nighttime applications and applications of non-labeled versions of dicamba (products other than the three listed above) likely caused many of the issues in 2017, though pesticide applicators dispute that.

And while last year applicators could apply when the wind speed was at 15 mph, now applications can only occur if the wind speed is between 3 mph and 10 mph, and that includes hard-to-predict Midwestern wind gusts.

When combined, these new restrictions will make it so the window of days applicators can actually spray dicamba may close altogether some years. According to the training documents, parts of Indiana only had about 48 hours last June when the wind speed and temperature specifications fit the new label requirements implemented this year.

Other restrictions were in place when the herbicides were first approved in 2016, but were reinforced during the training with the help of hypothetical examples.

A downwind buffer of 110 to 220 feet, depending on the product and application rate, is required when the wind is blowing toward a “sensitive area.”

It is not recommended that the product be applied at all, even up to three days after, if the wind is blowing in the direction of a particularly susceptible crop (such as conventional soybeans), according to a handout from the training prepared by University of Illinois, Purdue University and The Ohio State University extension offices.

The handout also stated that “in 2017, it appeared many applicators did not follow this restriction, perhaps because a specific distance to the sensitive area was not specified and sensitive crops and areas were not well defined.”

But gray areas remain, and many decisions will ultimately be left up to the applicator when they show up to the field, something the presenter mentioned several times during the training.

The class also covered the importance of selecting the right spray nozzle, cleaning out chemical sprayers after using dicamba – which, if not done properly, could lead to plant damage even at trace amounts – the importance of new record keeping requirements, and how subtle weather changes, like temperature inversions, wind gusts and rain can make the products more susceptible to move off-target.

Altogether, the instruction lasted less than one hour before certified applicators received their certificates to spray the herbicide this season.

The Illinois Fertilizer & Chemical Association said on Twitter that more than 5,400 applicators and farmers had attended the free training as of Feb.9, with 50 additional training classes scheduled through March 2018.