In the past you could usually count on a herbicide label staying relatively constant until the company made changes, such as in formulations. Dicamba herbicides for Roundup Ready 2 Xtend crops are setting a whole new trend in how herbicide labels are handled. These products include XtendiMax, FeXapan and Engenia.

Here are five key points to keep in mind about the dicamba herbicide system products as spraying season approaches. Bryan Young, a Purdue University weed scientist, provides the information.

1. There are now 20 nozzles approved for use with these products. When the products were first approved for spraying over dicamba-tolerant soybeans, only one spray nozzle was legal. Now the list is 20. Young says as the EPA has more time to review data on other nozzles, it continuously approves new ones and then updates the list on the label. Nozzles approved for use with these products must limit the amount of fine droplets to reduce the possibility of drift.

2. Many tankmixes are now approved for use with the dicamba products. Again, when the products were first registered just a short time ago, there were no approved tankmixes. The product had to be applied by itself, with nothing else in the tank.

Most, but not all, of the tankmixes approved so far consist of the dicamba product plus a residual herbicide. Residual herbicides are an important part of the dicamba system because they provide other sites of action. They also extend the length of control. Some will help pick up weeds that dicamba products are not as good at controlling.

3. There are no approved tankmixes with glyphosate yet. These are the mixtures everyone is waiting for because adding glyphosate with dicamba-based products provides a wide spectrum of weed control. Some formulations of glyphosate are now labeled for tankmixes with Engenia, Young says. No glyphosate mixtures are yet label for XtendiMax. One reason to continue checking the websites for label updates is to see if a glyphosate tankmix is added. If and when it’s added, language may restrict the type or rate of glyphosate for tankmixes.

4. These dicamba-based product labels represent a new effort to update labels via websites. Until now, EPA typically issued printed labels and seldom made changes. There are still printed labels, but the label itself refers you to a website to find updates. Logistically, EPA would find it virtually impossible to continue printing a new label each time a change is made in these labels. The products were registered with many decisions about use yet to be clarified. That’s why changes will be added on the websites: engeniatankmix.com, xtendimaxapplicationrequirements.com and fexapanapplicationrequirements.dupont.com.

5. The label actually requires you to check for updates no more than seven days before spraying. The update process of putting changes on the product website is not just a convenience, it’s actually part of the label, Young says. Checking a label’s website for possible updates no more than seven days before spraying is as much a label requirement as only using certain nozzles. It’s your responsibility to know what the most current label says, Young concludes.