Wallaces Farmer

Read your pesticide labels: Dicamba edition

Take extra precautions to prevent drift when using growth regulator herbicides such as dicamba.

June 5, 2020

6 Min Read
crop field
VOLATILITY: Herbicides containing dicamba have greater potential for moving offsite and injuring susceptible crops and plants. Farm Progress

To keep up with any changes and updates on pesticide uses and restrictions from year to year, it’s important to thoroughly read and understand the label before any applications are made, even if the same product was used the previous year.

“If nothing else, it helps to refresh your memory on the particulars of specific products that are applied to ensure optimum weed or pest control and environmental protection,” says Terry Basol, Iowa State University Extension field agronomist.  

Since 2017, growers have been able to use dicamba herbicide products labeled for over-the-top application on varieties of soybeans that have the dicamba resistance trait.  

“The first product to be labeled was XtendiMax with VaporGrip Technology, and now that list has grown to include Engenia, Fexapan plus VaporGrip technology, and Tavium plus VaporGrip technology as well,” Basol says. “The dicamba labels include extra precautions and application requirements to decrease the potential of off-target movement of dicamba.”

Dicamba, with its increased volatility, can drift to a nearby field of non-resistant soybeans, causing injury to the crop and yield damage. 

Training and certification 

As a reminder for the 2020 growing season, Basol explains the key recommendations and requirements that need to be followed when using these products. As always, be sure to read and follow the respective manufacturer’s dicamba label before application. 

All applicators applying dicamba products registered for use on soybeans with the dicamba resistance trait are required to annually complete dicamba or auxin-specific training. Information for face-to-face and online dicamba training in Iowa can be found at the Agribusiness Association of Iowa’s webpage: Dicamba Training in Iowa. The following factors need to be addressed:

Application timing and window. “In this article, we explain the main highlights regarding label requirements for dicamba use; all of the requirements are not listed here,” Basol says. 

The first requirement to keep in mind is that applications must occur between one hour after sunrise and two hours before sunset. Also, the labels recommend treating weeds early when they’re relatively small (less than 4 inches). 

Apply prior to beginning bloom (R1) growth stage of soybean plants, or no more than 45 days after planting, whichever comes first (XtendiMax and Fexapan). For Engenia, you can apply through beginning bloom (R1) or no more than 45 days after planting, whichever comes first. For Tavium, apply through the V4 growth stage, but no later than 45 days after planting. 

Recordkeeping requirements. Certified applicators must fill out records within 72 hours after application and keep them for a period of two years. Also, a record must be kept for each application. 

For training, you need to keep records of the date and provider of training, as well as proof of completion. For product label, keep a copy of the product label and any special local needs that supplement it. 

Keep a record of the crop planting date and the buffer distance calculation. Record that a sensitive crops registry was consulted and that the adjacent fields were surveyed prior to application. An example of a registry for Iowa would be FieldWatch, which can be found here.

At a minimum, records must include the name of the sensitive crop registry and the date it was consulted, and documentation of adjacent crops or areas and the date the survey was conducted, he says.

The time the application started and the time the application was finished needs to be kept. Also, record whether the application was a preemerge, postemerge, etc., and the number of days after planting if postemerge. Record the air temperature in degrees F at both the beginning of the application and after. Record the wind speed and direction at boom height at the beginning of the application and after. 

Record the spray nozzle type, manufacturer, orifice size and pressure for each application. For tankmix products, record brand name and EPA registration number for all products that were tankmixed. For sprayer system cleanout, keep a record of your compliance with the label of each manufacturer’s “Proper Spray System Equipment Cleanout” section.

Sprayer setup and adjustments. Regarding the spray volume, apply in a minimum of 15 gallons of spray solution per acre. Do not exceed a ground speed of 15 mph. Slower speeds will result in better spray coverage and deposition on the target area. If possible, reduce speed to 5 mph at the field edges. 

Do not exceed a sprayer boom height of 24 inches above the target pest or crop canopy. Pay attention to wind speed. Only apply when wind speeds measured at the boom are between 3 and 10 mph. 

Nozzles and tankmix partners. Specific nozzles and operating pressures are prescribed for these dicamba products. Information on approved nozzles can be found at each respective manufacturer’s website. Only products that have been approved for tank-mixing with these dicamba products can used in combination. These products can be found on the manufacturers’ website. Because changes and updates can happen readily, it’s good to periodically check this list to keep up with the options that are available to you. 

Manufacturer websites for nozzles and tank-mix partners: 

Buffer requirements, sensitive crop protection. There are buffer requirements to protect sensitive crops nearby the field where you are spraying dicamba. 

The applicator must always maintain a 110-foot downwind buffer for any application. For XtendiMax and Fexapan, if applying greater than 22 fluid ounces per acre (not to exceed 44 fluid ounces) in a single application, a 220-foot downwind buffer needs to be maintained. Refer to each respective manufacturer’s label to determine what areas can be included in the buffer distance calculation. 

Do not apply dicamba products when the wind is blowing toward adjacent non-dicamba tolerant sensitive crops, which includes non-dicamba tolerant soybean.

Endangered species concerns. New for 2020, applicators are required to obtain an Endangered Species Protection Bulletin before a dicamba application is made. This is a protection measure instituted by EPA for endangered or threatened species that may reside in the county where the application is to take place. A bulletin can be accessed up to six months before pesticide application. For more information on this and how to obtain a bulletin, read the ICM Blog post by Meaghan Anderson, ISU Extension field agronomist, titled Read your pesticide labels: Endangered species edition

Summing up

“The new dicamba products used in combination with dicamba-resistant soybean varieties have given growers another added tool in the toolbox to help with weed management and weed resistant strategies,” Basol says. “However, in order to allow these products to be used in the market as long as possible to meet the weed control needs of farmers, it is imperative that the label is read and followed by all applicators that use these products.” 

Source: ISU, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset. 




Subscribe to receive top agriculture news
Be informed daily with these free e-newsletters

You May Also Like