After receiving at least 242 Dicamba damage complaints from growers in 19 counties, the Arkansas Plant Board voted June 23 to suspend Dicamba use on all agricultural fields except pasture. Before taking force, the rule needs approval of Arkansas Governor Hutchinson and the Arkansas Legislative Council.
June 24, 2017 — Arkansas is the first state to take formal action in response to outbreaks of complaints about Dicamba drift damage. These incidents have occurred despite extensive precautionary application rules and technical anti-drift improvements in the product, made by BASF.
Monsanto markets the only Dicamba-tolerant soybean varieties, and other soybeans are extremely sensitive to the chemical. The most visible sign is leaf cupping. The symptoms may not cause serious yield loss but they’re very obvious, and often occur well outside the label-required spray isolation zones. The nearby photo, courtesy of the Arkansas Cooperative Extension Service, shows an example.
Here’s a link to a summary report posted on the University of Arkansas Public Radio website.
June 27 update: Farm Journal’s Chris Bennett reports Tennessee extension and government specialists are receiving a rising number of dicamba drift complaints.
Some of our WakeUP clients have asked us for ideas on how to make safer use of dicamba, which they see as at least a temporary solution to infestations of resistant pigweed / palmer amaranth. Some have gone to spray hoods, and all take special precautions to avoid spraying in weather conditions that could amplify drifting. We generally avoid posing as herbicide advisors, intending to stick with what we know best: Mobilizing nutrients into crops with WakeUP.
However, here are three ideas we’ve picked up from farmers and others who want to be good neighbors.
1. Spray at the quietest time of day, usually from 5 to 8 in the morning. Watch for wind advisories. A good website that shows an hourly graph of predicted wind speeds is Weather Underground: https://www.wunderground.com
At the home page, enter your zip code and, under the 10-day Weather Forecast section, click on “Graph.” You should see the continuation graph of wind speeds and direction at the bottom of the graph. This is a good site to bookmark on your smart phone.
Morning is also the least likely time of day for occurrence of a temperature inversion, which can have the effect of driving drift horizontally, low on the ground. University of Minnesota Extension specialists have a detailed explanation at this link.
We’ve never observed a reduction in spray effectiveness if there’s some dew on the leaves in the morning. University of Nebraska foliar application research also found early mornings an effective time for spraying, as leaf metabolic activity is just accelerating in its daily cycle.
2. Avoid spray tips and high pressures that produce fine droplets and mist. If you include 5 ounces per acre of WakeUP Summer in your spray blend as the only added surfactant, a droplet of any size will sheet out over the weed leaf and quickly absorb. You do not need a fine spray, which amplifies drift and volatilization. More water — 15 to 20 gal. per acre — and medium to coarse spray tips with moderate pressures can give you a glossy coverage on weed leaves. The sheen of spray moisture should absorb in only a few minutes, not linger on the leaf surface where it can evaporate. This is a result of WakeUP Summer’s unique colloidal micelle structuring of water — a different means of reducing surface tension than ordinary surfactants. With WakeUP Summer in the tank, you don’t need a mist for good leaf coverage.
3. If you’re using 30-inch soybean rows, consider spray nozzle extensions that place some tips low, between rows, and allow directional adjustments with swivels. We’ve found these effective as long as bean rows have 8 or 10 inches of spray distribution space between rows. That moves part of your spray delivery below the canopy. We don’t have any data on how effective spray hoods really are, but the manufacturers can probably help you with that information.
All these techniques can also help you effectively deliver foliar nutrients, too. This is what we’ve worked on, using WakeUP Summer, for almost 10 years.
Another profitable idea, as long as you’re heading to the field with a sprayer: Consider including a biostimulant, Vitazyme, piggybacked with the herbicide blend. It’s a biostimulant with a long-proven track record. And this season, we’re marketing it for the first time based on those years of research. It’s a natural partner with WakeUP Summer. In 2016, one of our farmer research cooperators ran a split-field soybean trial with Vitazyme mobilized by WakeUP Summer and saw a 10-bu. gain. That’s not a random-rep trial, but the results are vivid enough to show up on the yield map generated by the combine monitor. The makers of Vitazyme, Vital Earth Resources, show this and many other field trials in a PDF report you can download at this link.
We have Vitazyme available in 2.5-gal. jugs, plus 55-gal. drums and bulk totes.
Crop consultant Bob Streit of Boone, Iowa offers more background on the Dicamba issue. Below is an excerpt from his weekly Crop Watch column, available in full at this link:
One of the big stories of last season was the haphazard release of the Dicamba tolerant soybeans and the labeling of the companion herbicides. What was feared most was the drift potential of this family as either particle or vapor drift. The news that major problems occurred in states such as MO, AR and other Delta states and even a few farmers were killed over the issue garnered attention. This lead to a split in grower attitudes and whether they wanted to charge into the use of this tandem mix of products.
In Arkansas only temporary licensing was granted based on whether drift complaints remained at minimal number or if they would come flooding in. Well as of last week the reports told that the Depts. of Ag in several states were getting quite a few complaint calls and those permits may be rescinded. We can only wait to see what the outcome might be on this issue. Has any formulating company truly been able to tame this high vapor pressure chemical? If the German chemists are having problems, that is likely a harbinger of future problems.
As discussed in the ‘Chat N Chew Café Purdue Univ. website they included a good discussion about air inversions, and how and when they happen. That phenomenon occurs just before sundown as the air cools and either goes about mixing with warm air, or does not mix with warm air. This leads to sprayed particles remaining suspended until the light breezes that occur just after sunrise carry those particles up to and over a mile in distance. In other words the chances of these inversions are very common and out of human control. Being observant of separation requirements, wind speeds, nozzle types and pressures are all necessary and important, but there are still outside events that can lead to problems. So can Dicamba beans coexist with all other crops? We will know more by this fall.
AgWeb Technology Editor Chris Bennett also writes a detailed summary of what he calls the dicamba “chaos.”