As many speakers over the past few months have rightly pointed out, dicamba has been used within the agricultural marketplace to control weeds for several decades now. “The difference today is that we are applying it at times of the year when it was never applied before,” say most. “And that’s become the problem.”
In many cases during 2017, custom applicators working with dicamba products on dicamba-resistant crops ran into problems with off-target movement caused by a number of factors, according to experts. In particular, said Dr. Mark Hanna, a trainer for BASF, a big part of the problem is the fact that it takes very little dicamba accidentally left in a self-propelled sprayer to cause unwanted crop damage.
“It takes 3 milliliters of dicamba to contaminate a 1,000-gallon solution tank,” said Hanna, speaking at the 2018 Ohio AgriBusiness Association (OABA) meeting in February. “That’s essentially the same amount of liquid you would find in a syringe.”
During 2017, likely due to small amounts of dicamba accidentally left in sprayers and other factors such as unfavorable weather conditions, state agricultural agencies were inundated with crop damage complaints from growers across the eastern part of the country. In all, almost 3,000 complaints were filed, say experts, with the largest concentrations occurring in Arkansas (986), Missouri (310), Minnesota (250), and Illinois (245).
For 2018, this has led to several rule changes for dicamba applications across the country. For starters, says Ryan Rubischko, North America Dicamba Portfolio Lead for Monsanto, dicamba is now listed as a Restricted Use Pesticide (RUP). This means that only licensed commercial applicators are allowed to purchase it for use. In addition, there are now restrictions in place against applying dicamba after sunset/before sunrise and in wind speeds less than 3 mph.
The other significant change for 2018 is that all applicators that plan to work with dicamba during the growing season will need to undergo training from the states in which they do business. According to Doug Owens of the Illinois Department of Ag, his state has been conducting these training sessions since the start of the year. “Compared with other states, we are way ahead of the game,” said Owens in mid-January. “To date, we’ve had more than 3,000 applicators complete the required training.” However, he pointed out, with an estimated 15,000 applicators in Illinois, the state’s work has just begun.
Besides all these changes, industry watchers say that two sectors of custom application work will receive renewed attention in 2018 when it comes to dicamba work — paperwork and cleaning.
In most states, applicators using dicamba in 2018 will have 14 days to fill in the necessary paperwork noting such factors as the amount sprayed, wind speed at the time of application (both start and finish), and how many acres were applied. However, in a few places such as Ohio, this initial paperwork must be completed on the day of application, with additional documents with even more details being finished within 14 days of the work.
These records must be kept by applicators for a period of two years following dicamba application. Furthermore, says Keith Buckingham, a representative for Monsanto, applicators must have these records immediately assessable at the time of inspections. “If you utilize an electronic recordkeeping system, you must be able to readily access these records,” says Buckingham. “Our recommendation is to complete the label’s recordkeeping requirement after each application and keep those records on hand.”
But the paperwork goes beyond even this. According to BASF Ohio Representative Don Schneider, paperwork needs to be kept that details how sprayers were cleaned between dicamba and other herbicide application work. In other cases, speakers have reported that some ag retailers are even keeping paperwork on hand detailing what products are being transported to customer fields in their tender trucks, just in case any issues come up later.
Schneider explained why keeping all this paperwork could be important for custom applicators and ag retailers, especially after the fact. “One of the things that throws people off is dicamba drift won’t show up with cupped leaves for a few weeks after the application was done,” he said at the 2018 OABA meeting. “It won’t affect older leaves. But it does show up once the new leaves start to appear. That’s why keeping track of everything done when using dicamba is important.”
Sprayer Cleaning Considerations
When it comes to sprayer cleaning, this must be done before and after dicamba applications when the unit is being switched over to another herbicide. According to Dr. Fred Whitford, Director of Pesticide Programs for Purdue University, some herbicide residue can become embedded in a sprayer’s tank lining if it contains pits or dents. This same condition could also exist in a sprayer’s hoses, particularly if they are made of rubber. “There are newer hoses now on the market made of a polyethylene-rubber blend that can resist this kind of damage,” added Whitford, speaking at the 2018 Illinois Fertilizer & Chemical Association meeting.
Booms themselves need special attention to be properly cleaned out between uses. According to Whitford, a 120-foot boom can contain up to 35 gallons of liquid after the pump loses its prime. “This amounts to one to three acres of product left in the boom and hoses, depending upon the application rate,” he said.
Of course, by far the most common place in a sprayer for leftover herbicide to “hide,” he said, was in the end-cap of the boom itself. “There are still tons of machines out in the market that have a set-up where the end-caps of the boom piping can serve as a dead space for product to accumulate and stay between cleanings,” said Whitford. “That’s why I recommend installing some kind of coupler or valve to the end to allow for easy access and clean-out between uses.”
Finally, said BASF’s Hanna, applicators need to remember to thoroughly wash the exteriors of their sprayers when switching from dicamba to other herbicide applications. “Naturally, this should be the final step in the cleaning process for sprayers before any applicator takes them into a field that contains plants that might be susceptible to dicamba damage,” he said.