Pratap Devkota, UF/IFAS Weed Specialist, West Florida Research and Education Center

On June 3, 2020 the Ninth Circuit Court of Appeals vacated the registration of Xtendimax, Engenia, and FeXapan herbicide labels. Since this recent development, the US EPA has issued a cancellation order, followed later by an additional statement of clarification. The clarification from US EPA outlines the process and provides guidelines for compliance. The key points for growers are included below (follow the link for entire statement).

“EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan.
1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020.”


Glyphoste resistant palmer pigweed in cotton

Cotton field infested with glyphosate resistant Palmer pigweed. Do not let Palmer pigweed get this big, only option at this stage will be to hand remove. Credit: Pratap Devkota, UF/IFAS

With the recent developments on dicamba registration, the product cancellation timeline or allowed spray timeline (which is July 31, 2020) should be carefully noted. Another important consideration is using dicamba products following all aspects of the label, and factoring field conditions/surroundings to prevent off-target movement and injury to sensitive crop or plant species. In addition to reading dicamba herbicide labels carefully, the Florida Organo-Auxin Herbicide Rule needs to be followed for dicamba application (FDACS 2010). Here is quick summary on important information for dicamba application.

Dicamba Application Requirements

Pesticide License Requirement

XtendiMax, Engenia, FeXapan, and Tavium herbicides are “Restricted Use Pesticides” and only the certified applicators with valid RUP License are allowed to purchase and apply these herbicides. Before starting to apply dicamba, applicators are required to attend the Florida Dicamba Stewardship Training and receive a certificate as a proof of attendance. Please contact UF/IFAS Extension Office in your county for this training.

Dicamba Products

There are various dicamba products available in the market; however, only products labeled for dicamba cotton can be legally applied. Currently, approved dicamba products are XtendiMax, Engenia, FeXapan, and Tavium. The common “Banvel-type or Clarity-type” products cannot be applied to dicamba cotton.

Tank Mixing Herbicides or Other Products

Only the products recommended on Xtendimax, Engenia, FeXapan, or Tavium labels can be tank mixed. Complete list of the recommended tank-mix products for these herbicides can be found in the links below:

Ammonium Sulfate

Ammonium sulfate (which is commonly used water conditioner) cannot be mixed with newer dicamba herbicides. Adding ammonium sulfate increases volatility of dicamba and increases risk for off-target injury.

Buffer Requirement

A 110 feet downwind buffer is required for dicamba application. In addition to the downwind buffer, a 57 feet omnidirectional buffer (buffer in all sides) is required in counties where endangered species are present. For Florida, the omnidirectional buffer is required for Jackson, Washington, and Calhoun counties.

Using the Right Nozzles

Only certain nozzles and pressure combinations are allowed for applying dicamba herbicides. It is important to note that use of any nozzle not specifically approved and listed on these websites would be considered a misuse. There are various combinations listed in the link below for each dicamba product.

Spray Boom Height

A maximum boom height of 24 inches above the soil surface or the crop canopy is recommended. Exceeding this height can dramatically increase potential for dicamba drift.

Wind Speed and Direction

Applicator should pay close attention to the wind speed/gusts as well as direction before and during application. The wind speed/gusts should be 3 to 10 mph during application. Spraying must cease if the wind speed/gusts is higher than recommended or if the wind is blowing towards a sensitive crop.

Spray/Ground Speed and Spray Volume

The ground speed cannot exceed 15 mph while spraying in the field and 5 mph is recommended during spraying at field edges. Higher ground speed may result in vortex effect behind the sprayer and contribute to off-target movement. Spray volume needs to be at a minimum of 15 GPA.

Tank Clean-Out Procedures

Follow triple-rinse clean-out procedure by using: a) water; b) detergent based cleaner or commercial tank cleaning solution or 3% ammonia solution; and c) water. Do not let dicamba sit in the sprayer overnight.

Record-keeping Requirement

Recordkeeping is mandatory on dicamba application. Applicators must generate records within 72 hours of applying these herbicides.  A separate record must be maintained for each field or application. All records must be kept available for at least two years.


Florida Department of Agriculture and Consumer Services. 2004. “5E-2.033 Organo-Auxin Herbicides: Restrictions and Prohibitions.” Florida Department of State Florida Administrative Code & Florida Administrative Register. Available at: