Early-season weed control sets fields up for a successful crop season by removing weed pressure to start with a clean slate. Since weed systems are less complex this early in the year, achieving efficacy is easier in early-season burndown applications. However, it’s still essential to ensure effectiveness, especially for weeds that can cause more problems later in the season. Burndown is all about setting up efficient weed control strategies that will last through harvest. Adjuvants play a crucial role in creating an optimum tank mix for effective burndown applications.
If a field is not cleared with burndown or tillage, weeds will continue to grow, developing harder stems and more growing points, making them more challenging to control. The larger weeds compete with and hinder the growth for newly planted crops. No-till fields can struggle with winter annuals that soak up moisture, like henbit or purple deadnettle, yellow rocket, or pennycress. This leaves soil drier to start and could lead to further challenges, especially in years with low rainfall.
While some winter annuals die off or are killed with tillage or a simple burndown application, others may linger into planting season or be resistant to specific actives. For example, Marestail (horseweed) can stick around into the summer and is one of the toughest to kill because of glyphosate resistance.
A hidden benefit to burndown applications is a jump on managing pests like Lepidoptera (corn borer) as well as soybean cyst nematode. Winter annual weeds can house these pests that attack crops once planted. Pests like soybean cyst nematode can also lead to diseases that can be very detrimental. Controlling weeds that harbor these other pest problems contributes to integrated pest management.
Pest on soybean plant
The primary active ingredients for burndown applications, glyphosate, 2,4-D, and dicamba, are commonly paired with saflufenicil to fight tougher weeds for a more complete kill. Gramoxone is also very effective as a burndown herbicide, but it is becoming more regulated and used less in the field.
Many active ingredient labels require or recommend adjuvants to enhance efficacy and overall effectiveness. Adjuvants can increase herbicide coverage and penetration, improve tank mix compatibility, and many other functionalities impacting application performance. Be sure to read the label of your active ingredients to ensure essential adjuvants are included in your tank mix.
Getting a complete kill is the main goal of a burndown application. By improving coverage of the active ingredient over the weed and increasing penetration into the weed, MSOs give active ingredients a leg up for any active ingredients that benefit from the addition of oil-based adjuvants.
Certain weeds like marestail can be hard to control without proper application. Sticker spreaders make applications more resistant to environmental factors that can impede an application. The sticker assists the spray in adhering to the target, while the spreader increases the droplet’s coverage area. This forms a protective layer that improves the performance of the pesticide over time.
Surfactants are particularly important to improve the effectiveness of glyphosate and decrease the risk of resistance. Surfactants increase efficacy by lowering the surface tension of spray droplets to enable the tank mix to spread evenly over the leaf surface.
Surfactants Explained
Mixing multiple active ingredients together can be tricky. Adding a compatibility agent can prevent issues if two products don’t get along. Jar tests are important to ensure a tank mix will work and help determine if a compatibility agent is needed.
Ensuring there is enough water conditioning agent to combat hard water is essential to application effectiveness. Since water hardiness varies by location, this is more important for applications in hard water regions.
Using a mix of adjuvants is key to ensuring an effective application. Rather than tank-mixing individual adjuvants, multifunctionals are easy-to-use products that provide multiple adjuvant functions. For example, MSO/water conditioner and NIS/water conditioner multifunctionals are great options for burndown applications since many burndown active ingredients recommend an MSO or NIS.
Not all active ingredients are created equally, and it is crucial to select the right adjuvant with your active ingredient. The use of spray adjuvants helps maximize the success of burndown herbicide applications by ensuring that the active ingredient reaches the targeted weeds. Many labels recommend or require certain adjuvants to help with common challenges faced when applying that herbicide. Be sure to check the label of your active ingredient to ensure your tank mix has the best chance of achieving a complete kill.
Burndown applications with glyphosate typically call for ammonium sulfate (AMS) and a surfactant. Surfactants improve leaf coverage and aid in leaf penetration. In hard water regions, using a water conditioner helps to ensure that tank mix water does not antagonize the active ingredients. Broadleaf-focused herbicides benefit from using oil-based activator adjuvants to penetrate leaf surfaces and get into the plant. The efficacy of the application is reduced if tank mix ingredients don’t play well together, but this can be solved with a compatibility agent.
Effective burndown applications start the season correctly and lay the foundation for a successful weed management program for the remainder of the year. Selecting the proper adjuvants with your burndown program can make the difference between a successful start of the season or crops competing with weeds and disappointing results at harvest.
Pre-emergence herbicide applications offer a valuable tool to prevent or reduce weed infestations early in the season. While these applications are helpful, it can be a challenge to achieve optimum results. Adjuvant use is increasing and studies continue to prove their effectiveness.
Leaders from Exacto and other companies recently took part in advocacy activities in Washington, DC, engaging in twenty-four meetings with congressional leadership, senators, and the Environmental Protection Agency (EPA). They addressed a major challenge related to the Endangered Species Act (ESA).
Failed weed control may resemble herbicide resistance, but it’s not always the culprit. Recent cases of HPPD-inhibitor (group 27) herbicide failures have shown that certain application errors are more common culprits than resistance. This research shows ways to overcome these application challenges.
Cutting-edge discussions on golf course maintenance, including adjuvants and wetting agents, took place at the 2024 GCSAA Conference. The Exacto team was in full swing, bringing spray adjuvants, wetting agents, and innovative formulations to the table.
Have you ever thought you prepared the perfect application, but gotten less-than-perfect results? As the largest component of a spray tank mix, water can significantly impact application quality with hardness, pH differences, or dirtiness. Water conditioners can help to mitigate these issues.
Oil and water might not mix alone, but with the right emulsifier, they can be combined into a stable emulsion. The fascinating science behind emulsion stability reveals how adding the right emulsifier to a pesticide tank mix can ensure a uniform and consistent application.
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