Excessive rainfall during the first half of the 2015 growing season brought its share of weed control challenges to growers across Iowa. Wet field conditions made it difficult to apply postemergence burndown herbicides needed to start the season with clean fields and keep fields clean until the crop was emerged and growing well.
Herbicide-resistant weeds also continued to be a problem as there are 10 documented cases of resistance across Iowa.1 Waterhemp is among the most troublesome. And, judging by the number of waterhemp plants in fields at harvest, the spread of glyphosate-resistant waterhemp continued this year.Start 2016 weed control planning now and follow a program approach including herbicides with multiple modes of action. When used as part of a program approach, new technology such as the Enlist™ Weed Control System and timely postemergence applications of Enlist Duo™ herbicide at full label rates will help take control of the toughest weeds.
Despite these challenges, we did see clean fields. In fact, 2015 reinforced the value of using a strategic weed control program including soil residual herbicides at the correct rates. Growers who were able to make applications of preemergence residual products this year successfully held back weeds until postemergence applications could be made.
Keith Kenny deals with waterhemp and hard-to-control ragweed on his Schaller, Iowa, farm. This year, he applied a tank mix including Sonic® preemergence herbicide to control weeds in soybeans.
“I like using the preemergence herbicides to control weeds right after planting,” Kenny says. “Preemergence residuals are especially important if you get a long rainy spell and you can’t get in to spray.”
Kenny was among select growers who had the opportunity to experience the new, breakthrough technology of the Enlist™ Weed Control System and the benefits of Enlist Duo™ herbicide this summer.
“I’ve had problems controlling waterhemp for a couple of years, and Enlist Duo controlled it completely. I was very happy with the weed control I got from Enlist Duo,” Kenny says.
Enlist Duo, a combination of new 2,4-D choline and glyphosate, provides an additional mode of action to help control tough and resistant weeds.
Prepare now for 2016
We can’t control the weather, but the challenges it presented in 2015 offer some important weed management reminders for 2016 planning. Keep in mind: Weed escapes left many fields with significant weed pressure at harvest, causing buildup of the weed seedbank, which can impact a field for many years. Waterhemp generally produces about 250,000 seeds per plant. Like most weeds, the seeds remain viable in the soil for several years.
Begin with scouting, delay tillage
It is important to scout fields this fall and understand the weed spectrum in each field. Field tillage should be held off as long as possible to allow the weed seeds that are there to germinate and begin growing. Actively growing weeds then can be controlled with fall burndown, tillage or by frost.
Program approach to start clean, stay clean
Start 2016 planning by using a program approach including broad-spectrum soil residual herbicides with multiple modes of action. Be sure to apply them at full, recommended rates and follow label directions for application. This will help provide effective control of tough and resistant weeds.
By learning from the weed challenges of 2015, you can put together a program approach that will help you start with clean fields in 2016 and control weeds throughout the year.
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.
1Herbicide resistant weeds in Iowa, United States. Weedscience.org.
®™Enlist, Enlist Duo and Sonic are trademarks of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. Enlist Duo and Sonic are not registered for sale or use in all states. 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. ©2015 Dow AgroSciences LLC