JEFFERSON CITY, Mo. (DTN) -- Certain dates live in infamy. For some soybean growers, one of those dates may become June 12, 2024.

That's the cutoff date for over-the-top (OTT) application of dicamba herbicides for post-emergence weed control in soybeans in five states: Illinois, Indiana, Iowa, South Dakota and the southern half of Minnesota. This list includes four of the top five soybean-producing states in the nation. Last year, they combined to account for over half of the soybean harvest, totaling more than 2.12 billion bushels.

Currently, the three previously labeled OTT dicamba formulations -- BASF's Engenia, Bayer's XtendiMax and Syngenta's Tavium -- are being applied under an existing stocks order issued by EPA on Feb. 14. The order allowed for the use of the herbicide already distributed from the product registrants following application cutoff dates on the products' previously approved labels.

EPA's order came after the U.S. District Court for the District of Arizona in Tucson vacated those labels, finding that the EPA's "circular approach to assessing risk, hinging on its high confidence that control measures will all but eliminate offsite movement, (led) to its corresponding failure to assess costs from offsite movement."

The restrictions implemented by the EPA failed, and dicamba continued to vaporize and drift, the court said. As such, EPA was found to be in violation of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), leading to vacatur of the labels.

OTT dicamba applications in soybeans will continue to be permitted in the northern half of Minnesota and all other states where the products were previously label until June 30, 2024. The products' use in cotton is permitted until July 30, 2024.

After that date, no provisions currently exist that will allow these three dicamba formulations to be legally applied post-emergence over any crop in the future.

RULES FOR THOSE FINAL PASSES

As soybean growers in the five states with the June 12 cutoff date make those final herbicide passes, here are the applications restrictions still in effect:

-- After determining no adjacent sensitive crops and/or certain plants are downwind, the applicator must always maintain a 240-foot downwind buffer between the last treated row and the nearest downwind field edge when applying using broadcast open-boom equipment. In Illinois, the downwind buffer increases to 310 feet and 57 feet on all other sides of the field in areas where threatened or endangered species are located.

-- In Illinois, application is prohibited if the wind is blowing toward an adjacent residential area or any Illinois Nature Preserves Commission site.

-- Apply when wind speed is 3 to 10 mph.

-- Do not apply during a temperature inversion as the off-target movement potential is high. Applications may only occur one hour after sunrise through two hours before sunset.

-- In Illinois and Minnesota, OTT application in soybeans is prohibited if the air temperature at the field at the time of application exceeds 85 degrees.

-- Applications require that a volatility reduction agent (VRA) and drift reduction agent (DRA) is included in the tank mix.

IS OTT DICAMBA DEAD?

While these dicamba herbicides have no label for 2025 and beyond, the product registrants aren't going down without yet another fight. Both Bayer and BASF have submitted registration applications for XtendiMax and Engenia, respectively, to EPA already.

Bayer's new proposed label would remove any OTT application of the herbicide in soybeans and restrict its use to no later than June 12 in that crop in all states.

In dicamba-tolerant cotton, application would be allowed at-plant, pre-plant, preemergence and postemergence over the top, mirroring the previous label for XtendiMax. No applications would be allowed later than July 30, and the maximum annual application rate would be reduced from 88 ounces to 44 ounces in both soybeans and cotton.

Bayer made no changes to its product's formulation. A public comment period on this proposed registration and label ended June 3.

On June 4, EPA announced a 30-day public comment period for the registration and proposed label for BASF's Engenia herbicide. This label would allow applications to dicamba-tolerant soybeans and cotton made preplant, at planting, preemergence or postemergence over the top.

However, no OTT application would be allowed in soybeans once the crop reached the V2 growth stage -- when the second trifoliate leaf is fully unfolded -- or after June 12, whichever comes first. This date mirrors the one proposed by Bayer for XtendiMax but is earlier than the previous Engenia label.

In dicamba-tolerant cotton, no applications of Engenia would be allowed after July 30. This cutoff date is the same as the previous label and proposed for the new XtendiMax label.

In addition to the changes to OTT application and cutoff date in soybeans, the new proposed label cuts the total maximum number of applications from four applications to two applications, reducing the maximum annual rate by 50% to a total of 25.6 ounces per acre in both soybeans and cotton. The product formulation for Engenia is the same as previously labeled.

The last day to submit a comment regarding the proposed registration and label for Engenia is July 5, 2024. EPA will review public comments as part of the proposed application process and incorporate any feedback into the registration decision. To comment, go here: https://www.regulations.gov/…

To date, Syngenta has not publicly announced its plans for Tavium beyond the current existing stocks order. However, industry stakeholders anticipate the company will follow suit and submit a proposed registration and label for 2025. Whether the company will include any OTT application for soybean or reduce maximum annual rates on a proposed label is yet to be determined.

More stories from DTN on dicamba developments:

-- "Comment Period Opens on BASF Dicamba," https://www.dtnpf.com/…

-- "Comment Period Opens on Dicamba Product," https://www.dtnpf.com/…

-- "EPA Outlines OTT Dicamba Use for 2024," https://www.dtnpf.com/…

-- "Court Vacates Dicamba Registrations," https://www.dtnpf.com/…

Jason Jenkins can be reached at jason.jenkins@dtn.com

Follow him on social platform X @JasonJenkinsDTN

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