This week the university's Frequently Asked Questions Guide for RUP Dicamba Herbicides (FeXapan™, Engenia® and XtendiMax®) was updated to address new questions from growers. More questions may be added to the site from time to time so check back for further information before applying these products and please refresh your web browser to ensure you're viewing the latest version.

Following are two of the questions and answers added to the site this week:

What is the requirement for applying one of the new RUP dicamba products followed by irrigation or predicted rain?

The labels prohibit application if rainfall is predicted within 24 hours. Rainfall and irrigation are essentially considered the same, so irrigation should not occur until 24 hours after the application. The intent is to avoid runoff of the chemical that could result in uptake by non-target species.

Must I clean out my spray equipment every day when using the RUP dicamba products?

No. RUP dicamba labels require applicators to ensure that spray equipment is clean before using the product and after the product is applied. Cleaning equipment prior to loading with dicamba assures that nothing left in the sprayer will negatively impact the performance of the dicamba or the crop being treated. The RUP dicamba labels require spray systems be cleaned, following the procedures listed on the RUP dicamba labels, before using the herbicide after another type of spray mix, and immediately after using dicamba before switching tank mixes. This is to avoid contaminating the RUP dicamba spray mix with other chemicals that might affect the volatility of dicamba, and to avoid carrying dicamba over to a sensitive crop in the next load or applications.

Note: The NDA also advises applicators that all transportation equipment hauling pre-blended dicamba loads to the field are also potential sources of contamination, and should be treated the same as spray equipment when it comes to clean before changing product mixes.