Glyphosate resistant weeds, especially water hemp and palmer amaranth, are a reality for most producers across the soybean growing areas. If not already, there is no question they soon will be. The purpose of this discussion is not to dive too deep into actual herbicide recommendation, as that is a conversation that must happen on a local level to take in a grower’s specific needs on a field by field basis. It is instead a big picture look at weed control, yield potential and risk associated with the Genuity® Roundup Ready 2 Yield®, Liberty Link® and Roundup Ready 2 Xtend® systems.
Regardless of the system used, good management practices are:
- “start clean and stay clean” is a cliché, but also a truth in controlling weeds
- Provide clean tillage or complete burndown in a no till system
- Use 2 or more modes of action in residual herbicide mixes before planting, for improved weed control and weed resistance management
- Spray weeds when they are small
- Rotate herbicide modes of action
- Limit rescue operations of the “burners” Cobra®, Flexstar®, etc.… on big weeds, by being proactive with the use of soil residuals
- Limit fall tillage on weedy fields to leave the weeds seeds on top where they are eaten or become non-viable by spring
Also of value, are practices that promote quick canopy to keep weeds under control including:
- Use of fuller season products
- Selecting products that have a bushy/branchy profile
- Use of narrow rows
A short review of each of these systems follows:
Genuity® Roundup Ready 2 Yield® (RR2Y)
Weed control - There are clean fields of RR2Y soybeans this year and there are plenty that are not. A couple of the key points in the recommendations above were likely followed in these clean fields; having a second application of residual herbicide in crop and having a complete canopy. Late applications of burner herbicides look good for a while, but weeds often are not completely killed, break through, and continue to grow.
Yield Potential – Product lineup is mature with high level, proven performance
Risk – Certainly not a risk-free system but a very familiar system that is widely deployed today
Weed control – Liberty® herbicide works great in combination with a soil residual, and long as small weeds are targeted. Liberty must be treated as a contact herbicide, 18+ gallons of water per acre and complete target coverage.
Yield Potential – There are good products in this program, but it is not generally where we look for the maximum yield possible in a soybean product. There are not many new products in this platform.
Risk – Primary benefit is good weed control in a low risk level system and in a widely used familiar program
Roundup Ready 2 Xtend® (RR2Xtend)
Weed control – Weed control is excellent in combination with a soil residual and timely application to small weeds. One of the main benefits of this system is when used as a burn-down or as an early application in conventional tillage; there are no planting restrictions for RR2Xtend soybeans. Otherwise using this chemistry requires at least a two week wait before planting a susceptible soybean.
Yield Potential – Overall yield potential is expected by all to be the best, with lots of breeding going on in this space. Products are all new or nearly so and some need to be proven in the field.
Risk – There is substantial risk from this system primarily from drift, though volatility can also come into play if the label is not followed correctly. Key points are: spray applications need to be completed by R1, first flower, that is early and the earlier the better because of less risk of damage to nearby susceptible crops. The label has to be followed to the letter; no if’s, and’s, or but’s. If you don’t plan on doing that, use another system. New label requirements are likely to include a cut-off date for dicamba application early in the cropping season. This could be a downer by limiting use of the herbicide.
Some producers have elected not use the herbicide, but instead use RR2Xtend soybeans and control weeds as in a RR2Y system. Reasons for this are to gain the potential yield increases associated with the breeding, plus have the benefit of not having to worry about what the neighbor is spraying for herbicide.
A short review of the approval status future trait platforms
- Enlist™ – Still lacks China approval but this could happen before the next planting season. If it does gain approval, seed supplies would be very low. The herbicide is approved. Enlist™ is an interesting system and could gain some traction because 2, 4-D is not nearly as hot at low dosages as dicamba to susceptible crops.
- Balance® GT – Trait approved, herbicide is not. Bayer is not supporting this system because, while the Balance® herbicide is a good pre-plant residual, without Liberty® in the mix for follow-up, the system is very weak. Another issue is the HPPD family of herbicides already has weed resistance showing up. It could be a very short lived tool without the backup of the multiple modes of action that are in the Balance® GTLL system.
- Balance® GTLL – Anticipated 2019 approval. This system fixes the issues of the Balance® GT system with the addition of Liberty® herbicide tolerance.
- RR2XTEND + LibertyLink® – 2021 is anticipated approval status.
It is a complicated world with resistant weeds gaining traction and no easy or inexpensive herbicide systems available, all combined with a farm economy that leaves a lot to be desired. The best policy is to stay current and informed about all the options available.
LG Seeds has a good supply of conventional, Roundup Ready 2 Yield®, LibertyLink® , and Roundup Ready 2 Xtend® products to meet to our customer’s needs.
Note: The information in this issue is based upon field observations and third party information. Since variations in local conditions may affect the information and suggestions contained in this issue, LG Seeds disclaims legal responsibility therefore. Always read and follow label instructions.
Roundup Ready 2 Yield®, Roundup Ready 2 Xtend®, XtendFlex®, XtendiMax™ and VaporGrip™ are trademarks of Monsanto Technology, LLC. LibertyLink® and Liberty are trademarks of Bayer CropScience. Cobra® is a registered trademark of Valent U.S.A. LLC. Flexstar® is a trademark of a Syngenta Group Company. Enlist™ is a trademark of Dow Chemical Company. LG Seeds and design are trademarks of SCA Limagrain.
Download a copy of this Technical Bulletin: Tech_348 - Soybean Technology and Herbicide Systems Review