Dicamba Injury Is Back in 2018

Dicamba is once again injuring non-dicamba-tolerant soybeans in 2018. As of June 15, university weed scientists estimate that approximately 383,000 acres of soybeans have been injured by dicamba so far, according to Kevin Bradley, University of Missouri Extension weeds specialist. 

That’s out of an estimated 89 million acres of soybeans planted, according to USDA. Last year, dicamba damaged an estimated 3.6 million acres out of 89.5 million acres. That concerns Bradley, particularly if Xtend technology adoption increases in 2018 and beyond. Monsanto estimated 2018 Xtend acres to double from 2017 to 50 million acres in 2018.

Of the 15 state departments of agriculture that responded to this request for information, only 43 cases of alleged injury are currently under investigation in soybeans, says Bradley. However, the incidents and cases of off-target movement of dicamba to specialty crops, vegetables, ornamental species, and trees seems to be more prevalent this year compared with last season. They constitute some 111 of the remaining cases under investigation.

Soybean injury by acres in individual states are below:

• Arkansas 100,000
• Illinois: 150,000
• Indiana: 5,000
• Iowa: 1,200
• Kansas: 100
• Kentucky: 500
• Nebraska: 40
• Missouri: 25,000
• Mississippi: 100,000
• Tennessee: 2,000

No soybean injury from dicamba in the rest of the states that reported has occurred so far. These states include Michigan, Minnesota, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Virginia, West Virginia, Wisconsin, and Texas.

Damage to “Other Crops”

Bradley has witnessed an increasing problem of off-target dicamba injury to “other” crops and tree species in calls he’s received, field visits he’s made, and “windshield surveys” of Missouri that he’s taken the past few weeks. The problem is especially apparent in southeastern Missouri last week, he says.

“In this region, I’m convinced that the adoption of the Xtend trait in cotton and soybeans is as high as anywhere in the country,” he says. “Many growers in this area have adopted the Xtend trait so they don’t experience dicamba injury on their soybean crop for a third season in a row.

“Since the adoption of the Xtend trait is so high in this area, relatively speaking there seem to be fewer soybean fields with injury this year compared with last,” he says. “However, just as in the past two seasons, there are still fields of non-Xtend soybean in this area showing injury from one end to the other.

“More surprising to me than that has been the extent of the trees that are showing symptoms of growth regulator herbicide injury in that part of the state where the adoption of this trait is so high,” he adds.

Cotton Injury

Several of Bradley’s university colleagues who work in cotton have been encountering calls and field visits pertaining to off-target movement of 2,4-D onto cotton as well. That’s presumably a result of the increase in the adoption of the Enlist cotton trait, he says. Non-Enlist cotton is about as sensitive to low doses of 2,4-D as non-Xtend soybean are to dicamba, says Bradley.  

While very few of these incidents have been officially filed with the state departments of agriculture, the estimates below tally the cotton acreage that university weed scientists say has been injured by either 2,4-D or dicamba as of June 15.

Arkansas acres

2,4-D injury: 5,000

Dicamba injury: 0

Mississippi acres

2,4-D injury: 5,000

Dicamba injury: 10,000

Missouri acres

2,4-D injury: 1,500

Dicamba injury: 0

Oklahoma acres

2,4-D injury: 2,500

Dicamba injury: 0

Tennessee acres

2,4-D injury: 2,500

Dicamba injury: 100

Texas acres

2,4-D injury: 450

Dicamba injury: 180