Weeds are every farmer’s archnemesis because they rob your crop of water, sunlight and nutrients, while decreasing the crop’s yield potential. Adding to the challenge is the increasing incidents of herbicide resistant weeds. Prolonging the lifespan of important herbicide active ingredients is critically important while also decreasing the occurrences of herbicide resistant weeds.
To minimize the potential for herbicide resistance in your field, it’s important to establish a weed management program that incorporates multiple modes of action. That’s where herbicide layering becomes an effective strategy. Herbicide layering is the practice of using multiple herbicide modes of action in a specific order to combat tough weeds and reduce the development of herbicide resistance.
“The concept of herbicide layering, in my mind, is critical for weed management in corn and soybeans,” says Ryan Henry, UPL Technical Services Development Manager for Herbicides. “Farmers need an appropriate weed management strategy that layers herbicide applications to help manage the weeds throughout the growing season, especially at planting.”
The Reason for Herbicide Layering
Henry, who has a hand in the research and development of herbicides for UPL, explains that each weed species has strengths and weaknesses that a herbicide has to meet.
For example, in a field you can encounter a variety of different weeds including perennial and annual grasses and small-seeded and large-seeded broadleaf weeds. It’s very unlikely to have a field with just one weed variety or monoculture. One weed might have an established dominance over others, but there will still be multiple weed types in a single field.
In addition, each weed might have different germination profiles. Germination of weed seed is affected by environmental conditions, changes such as temperature fluctuations, increased humidity and longer days.
When considering those factors, growers will need to combat varying conditions and timing for effective weed control. Herbicide layering uses pre- and post-emergent applications along with multiple modes of action to establish a weed management program that targets weeds at the right time.
Benefits of Herbicide Layering
- Ability to control weeds at germination and post-emergence before the three- or four-leaf stage.
- Limiting selection pressures against individual modes of action can be achieved by reducing the number of individual weeds and managing portions of a population that have developed resistance.
- Reaching your crop’s full yield potential by controlling weeds before they can compete with the crop for nutrients.
- Pre-emptively working against herbicide resistance.
- Avoiding overuse of herbicides and reducing selection pressures.
The Ideal Herbicide Layering Program
Developing an herbicide layering program includes choosing products that have different modes of action throughout the season. After choosing which herbicides to use, the next is when to apply them. The most traditional herbicide layering program includes a pre-emergence application followed by a post-emergence treatment.
When choosing your herbicides, consider deploying multiple modes of action. For row crops, four modes of action is ideal.
Example Herbicide Layering Program for Enlist Soybeans
- Apply MOCCASIN MTZ herbicide as a pre-emergent application. MOCCASIN MTZ builds in two modes of action with its mixture of metribuzin and S-metolachlor.
- After the soybeans emerge, in a V3 stage or later, applying INTERLINE Herbicide tank-mixed with Enlist 1 as a post-emergent application adds two more modes of action.
In this program the application of MOCCASIN MTZ will control small-seeded broadleaf weeds and grasses and the application of INTERLINE will control glyphosate-resistant weeds.
Herbicide layering is a useful tool for weed management and can improve growers’ abilities to combat weed resistance. By using pre- and post-application timing and multiple modes of action, you are able to target weeds with different germination profiles. If you can decrease weeds and therefore increase your crop’s yield, why wouldn’t you try herbicide layering?
Ask your local retailer or UPL representative for more information on herbicide layering and to develop a program specific for you.
