Herbicide-resistant weeds are a hot topic for growers — and for good reason. If you don’t follow proper weed management recommendations, you will get resistant weeds. One female pigweed plant can produce 200,000 to 1 million seeds, so it’s easy to see how weeds can take over quickly.

Matt Gilbert, a grower from Markle, Indiana, worries about the growing resistance on his farm in the last few years. Giant ragweed and marestail have become especially hard to control with high rates of glyphosate, he notes.

Giant ragweed and marestail are becoming harder to control on Matt Gilbert’s farm in Indiana. A few days after spraying, Enlist Duo herbicide provided exceptional control of giant ragweed and other weeds.

“Over the past five years, we’ve really started to notice growing resistance to glyphosate,” Gilbert says. “Recently, we’ve had to increase our rate of Roundup to significantly more than we used just a few years ago.”

In Indiana, growers should watch for marestail, ragweed (giant and common) and waterhemp.

Start with clean fields and make timely herbicide applications. Target the weeds when they’re small and actively growing. Also, remain vigilant. You may look at a patch of weeds in the field and think it’s because of sprayer skips or other boom issues, but do a little investigating. One or two weeds can turn into millions quickly.

To control these tough weeds, use a program approach to weed resistance management. Start with a preemergence herbicide, such as Sonic herbicide in soybeans or SureStart II herbicide in corn. Next, timely apply a postemergence herbicide, such as Enlist Duo herbicide for Enlist crops. The Enlist Weed Control System provides an additional mode of action to help control tough and resistant weeds.

Dave Hillger, Ph.D., Enlist field specialist, Dow AgroSciences

You may want to trim down your herbicide costs this year with commodity prices down. It’s a bad idea to reduce chemistries in your weed management program simply because one year of bad management could harm your fields and crops for years to come.

Take the following steps during the season to help manage weed resistance:

Spray when weeds are small. It can be challenging because of weather and other factors, but it is ideal.

Use full rates of the herbicides during applications. Do not use partial rates or trim back because of cost.

Use multiple modes of action. This becomes more limiting as resistance grows. This is a prime opportunity for the Enlist Weed Control System.

It’s important to have a plan for your season; that way, if weather delays occur or weed escapes happen, you’ll have an option already in mind.

And don’t underestimate the importance of properly functioning equipment.

Preparing the sprayer is key. Spend a day just calibrating equipment and making sure screens are cleaned. Check that nozzles match, and remember that the same color doesn’t mean it’s the same nozzle. Then, when you get into the field, you’re not struggling with breakdowns that could delay applications.

For on-target applications, remember to follow best management practices when applying a herbicide. Be aware of crops in surrounding fields and environmental conditions, such as wind speed, wind direction and signs of a temperature inversion.

For more information on the latest herbicide-tolerant trait technology available to help you manage hard-to-control and resistant weeds, visit the Enlist YouTube channel, follow on Twitter at @EnlistOnline or visit Enlist.com.

Trademarks of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. Enlist Duo, Sonic and SureStart II are not registered for sale or use in all states. SureStart II is not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. Contact your state pesticide regulatory agency to determine if a product is for sale or use in your state. Always read and follow label directions. copyright 2015 Dow AgroSciences LLC