DuPont Herbicide Programs for Waterhemp and Palmer Amaranth Control in Dicamba-Tolerant Soybeans
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Waterhemp and Palmer Amaranth
- #1 weed problem in many areas.
- Populations have developed resistance to multiple herbicide sites of action, including ALS, EPSPS, PSII, PPO, HPPD, synthetic auxins, and mitosis inhibitors.
- Both species are obligate out-crossers and prolific seed producers with a wide germination period.
Managing Waterhemp and Palmer Amaranth
- Start clean at planting – use tillage or effective burndown herbicides.
- Get to canopy closure as quickly as possible and weed-free.
- Narrow rows
- Good early season growth
- Use 2-pass (minimum) herbicide programs with multiple effective modes of action and overlapping residuals.
- Residual pre-emergence herbicides
- Include residual in post-emergence treatments
- Timely post-emergence application – weeds 4 inches tall or less.
- Cultivate where possible and manually remove escapes.
- Clean equipment to reduce movement of weed seed.
- Control weeds after harvest.
- Goal: prevent weed seed production.
DuPont™ FeXapan™ herbicide plus VaporGrip™ Technology
- Low-volatility dicamba formulation from DuPont.
- Designed for reduced volatility compared to older commercial dicamba formulations.
- New mode of action for in-crop use in soybeans with the dicamba-tolerant trait (label pending EPA approval).
- Currently labeled for other crops (e.g., corn, sorghum, cereals, etc).
- Use as part of a program with other herbicides and weed control techniques.
- Follow all stewardship requirements on final, approved label and all local regulations to help minimize off-target movement.
Research Objective
- Evaluate weed control efficacy and crop tolerance of DuPont herbicide programs for waterhemp and Palmer amaranth control in dicamba-tolerant soybeans.
Study Description
- DuPont field trials in 2016:
- 9 southern locations (7 with waterhemp or Palmer amaranth)
- 6 central locations (4 with waterhemp or Palmer amaranth)
- 5 northern locations (2 with waterhemp or Palmer amaranth)
- Randomized complete block design with 3 replications
- Herbicide Applications:
- Pre-emergence (PRE): immediately after planting
- Post-emergence (POST): 2 to 4-inch weeds
- Adjuvants: none
- Nozzles: TTI at 10-20 gallons/acre
- Evaluations:
- Crop tolerance: 0, 7, 14, and 28 days after POST treatment.
- Weed control: 0, 14, 28, and 42 days after POST treatment.
Table 1. Commercial names and active ingredients of herbicides used in pre-emergence (PRE) treatments in 2016 DuPont field studies.
Table 2. Commercial names and active ingredients of herbicides used in post-emergence (POST) treatments in 2016 DuPont field studies.
Results
Southern Locations
Table 3. PRE and POST herbicide treatments used at southern locations.
Table 4. Efficacy of weed control treatments at southern locations. Data from locations in OK, IL, KS, NC, AR, TX, and MS. Palmer amaranth at 6 locations, waterhemp at 2 locations.
Waterhemp control with two-pass herbicide programs, Marion, IA, 2016.
Waterhemp resistant to glyphosate, ALS, and POST-applied PPO herbicides.
Central Locations
Table 5. PRE and POST herbicide treatments used at central locations.
Table 6. Efficacy of weed control treatments at central locations. Data from locations in NE, MD, IL, and IA. Palmer amaranth at 2 locations, waterhemp at 2 locations.
Northern Locations
Table 7. PRE and POST herbicide treatments used at northern locations.
Table 8. Efficacy of weed control treatments at northern locations. Data from locations in NE and MN. Waterhemp at 2 locations.
Crop Response
- Low crop response (<10%) was observed from the herbicide treatments.
- Low crop response with both PRE and POST treatments
- Slight increase in crop response with POST applications of s-metolachlor
Summary
- DuPont enhanced PRE herbicides gave >90% early season Palmer amaranth and waterhemp control, reducing weed density for POST treatments.
- DuPont FeXapan™ herbicide plus VaporGrip™ technology boosted control to 95%+ with excellent crop tolerance.
- Addition of DuPont Cinch herbicide POST provided additional residual control through canopy closure.
Conclusions
- 2-pass herbicide programs that include DuPont enhanced PRE products followed by timely POST applications of DuPont FeXapan™ herbicide plus VaporGrip™ Technology provide growers with excellent Palmer amaranth and waterhemp control.
- Residual control can be further extended with the addition of a product like DuPont Cinch herbicide applied at POST timing.
Authors: Dave Johnson, Ph.D., Eric Castner, M.S., Robert Rupp, M.S., Richard Edmund, M.S., Dan Smith, M.S., Jeff Krumm, Ph.D., Kevin Hahn, Ph.D., Bruce Steward, Ph.D., Mike Meyer, Ph.D., Kelly Backscheider, Ph.D., and Victoria Kleczewski, Ph.D., DuPont Crop Protection
DuPont™ FeXapan™ herbicide plus VaporGrip™ Technology is not registered for sale or use on Roundup Ready 2 Xtend® soybeans or on other Xtend crops in the United States. No offer for sale, sale or use of this product for these uses is permitted prior to the issuance of the required EPA and state registrations.
DO NOT APPLY DICAMBA HERBICIDE IN-CROP TO SOYBEANS WITH Roundup Ready 2 Xtend ® technology unless you use a dicamba herbicide product that is specifically labeled for that use in the location where you intend to make the application. IT IS A VIOLATION OF FEDERAL AND STATE LAW TO MAKE AN IN-CROP APPLICATION OF ANY DICAMBA HERBICIDE PRODUCT ON SOYBEANS WITH Roundup Ready 2 Xtend® technology, OR ANY OTHER PESTICIDE APPLICATION, UNLESS THE PRODUCT LABELING SPECIFICALLY AUTHORIZES THE USE. Contact the U.S. EPA and your state pesticide regulatory agency with any questions about the approval status of dicamba herbicide products for in-crop use with soybeans with Roundup Ready 2 Xtend® technology.
ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Soybeans with Roundup Ready 2 Xtend® technology contain genes that confer tolerance to glyphosate and dicamba. Glyphosate herbicides will kill crops that are not tolerant to glyphosate. Dicamba will kill crops that are not tolerant to dicamba.
Roundup Ready 2 Xtend® is a registered trademark of Monsanto Technology LLC used under license.
The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. 2016 data are based on average of all comparisons made in 13 locations through Nov. 1, 2016. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.