Waterhemp Control

Trial Overview

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  • Herbicide-resistant waterhemp is becoming more prevalent in many growing areas and causing management challenges for growers. Properly timed postemergence herbicides can play an important role in the control of glyphosate-resistant waterhemp.
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Research Objective

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  • The objective of this study is to evaluate the control of glyphosate-resistant waterhemp in low, medium, and high input herbicide systems for three different soybean herbicide trait systems: Roundup Ready 2 Xtend® soybean (RR2X), Genuity® Roundup Ready 2 Yield® soybean (RR2Y), and LibertyLink® soybean (LL). 
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Location
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Elwood, IN
Clay Loam
Soybean
Conventional
05/19/2016
10/08/2016
N/A
140,000
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Site Notes:

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Soybean products included AG30X6 Brand (RR2X); AG2933 Brand (RR2); BK 298L4 Brand (LL). The trial was a split plot design with four replications. Soybeans were planted in 30-inch rows. Preemergence (PRE) herbicide treatments were applied on May 19, 2016. Postemergence (POST) treatments were applied on June 16, 2016 at the V2 soybean growth stage and when waterhemp was 4 inches in height. Treatments included an untreated, low, medium, and high input herbicide program for each trait block. Very little activating rainfall occurred within the 10 days following PRE applications. Glyphosate-resistant waterhemp was the predominate weed species present at the site and was the only weed species rated for control in this study. Weed control ratings were taken periodically throughout the season. This summary reports the findings from the preharvest weed control rating taken 18 days before harvest for each treatment.
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Understanding the Results

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*pending regulatory approvals. **EPA approved for in-crop use, pending state approval.
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  • The inclusion of Roundup Xtend™ herbicide with VaporGrip™ Technology (pending regulatory approvals)  brings value and works well with other herbicides in the system as seen with treatments 2, 3, and 4 (Figure 1). 
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  • A combination of PRE residual herbicides and timely POST applications of Xtendimax Herbicide with VaporGrip technology paired with a residual herbicide are necessary to achieve optimum control of heavy glyphosate-resistant waterhemp pressure.
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What Does This Mean for Your Farm

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  • This trial demonstrates that the inclusion of dicamba with the Roundup Ready® Xtend Crop System brings another effective mode-of-action to help control glyphosate-resistant waterhemp difficult weeds like glyphosate-resistant waterhemp.
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