Growing Knowledge

Read the latest insights from our experts as they cover agronomy issues that matter most to you and your operation.

Are Your Herbicide Sites of Action Effective?

Mark Glady
Regional Agronomist
As new herbicide technology hits the market, there has been even more discussion about the battle against resistant weeds. The International Survey of Resistant Weeds reports there are 160 weed species in the U.S. that are resistant to at least one herbicide class. But how does resistance happen and what can you do to help combat the problem?
Rise of Resistant Weeds
Resistance starts with a small number of weeds that carry mutations making them more tolerant to specific herbicides. This happens spontaneously, in the same way that mutations happen in our own DNA. The problem arises when we inadvertently give these weeds the upper hand by selecting for them when we apply herbicides that they are tolerant to.
Herbicide-tolerant weeds are selected for when there is a spray program that lacks diversity, meaning herbicides with the same sites of action are continuously applied. Every time a weed escapes control, it has the potential to make seed. Those seeds end up in the soil and the next generation of weeds have more tolerance to the herbicide they are developing resistant to. If the same herbicide class is used without including additional effective sites of action for control, the cycle continues until resistant weed populations have taken over.
Break the Cycle
The good news is that you can stay one step ahead of resistance by diversifying your spray program. The goal is to limit weed escapes by using multiple site of action herbicides in your tank mixes. It’s also important to layer herbicides throughout the season and incorporate residual products to get extended windows of coverage. These strategies all help attack the defenses of weeds that have become adapted to the environments they are thriving in.
Some weeds have documented resistance of up to four different sites of action, so don’t assume adding multiple site-of-action herbicides to your tank will be enough. Make sure the products you are using are actually effective against the weeds you are trying to control.
The website Take Action on Weeds has a tool that identifies sites of action for most common herbicides to help you diversify your spray program. Alternating herbicide sites of action can help extend product life and reduce the likelihood that weeds will develop resistance. Talk to your local retailer to learn more about effective weed management strategies.

Using Plant Growth Regulators and Nitrogen Stabilizers

Joel and Kyle
Hosts, WinField United
On this episode of The Deal With Yield, Joel Wipperfurth and guest host Jon Zuk discuss if plant growth regulators are a mainstay in today’s crop management plans. The guys also cover varying nitrogen management practices, crop models and decision trees.
Season 12, Episode 4: Using Plant Growth Regulators and Nitrogen Stabilizers

The Deal With Yield is a podcast series covering the issues that matter most in crop production.

Get Nitrogen Where It Needs to Be

Darrin Roberts
Regional Agronomist
There’s no doubt you want to get as much of the nitrogen you apply as possible into your crop. But studies have shown that for every 10 pounds of nitrogen fertilizer applied to cereal crops such as corn, less than 5 pounds are actually taken up by the crop.1 That’s a lot of lost nitrogen!
Here are some tips to help keep nitrogen accessible to your crop and prevent it from going where it shouldn’t.
1. Apply nitrogen when the crop is actively using it.
With nitrogen, timing is everything. If you apply nitrogen in the fall when crops aren’t growing, you could experience far more loss than if you apply it in the spring or during the season. Applied nitrogen can quickly convert to nitrate, which is highly mobile in the soil and may be prone to leaching into groundwater or tile lines if it is not taken up by the crop.
2. Include a nitrogen stabilizer.
If you do need to apply a portion of your nitrogen in the fall or prior to planting in the spring, include a stabilizer with it. With a stabilizer, you can extend the period of time  nitrogen is kept in ammonium form, which the soil can hold and make available for the crop to take up in-season.
3. Perform a soil and/or tissue test.
Talk with your agronomist about doing a pre-side-dress soil nitrate test (PSNT). The PSNT, which is usually performed in late spring, is done prior to your side-dress application to estimate how much nitrate you have in the soil and whether it’s sufficient to supply the crop’s nitrogen need until maturity. Tissue testing can also help identify nutrient needs at critical times during the growing season. In addition, you should soil test every couple of years for phosphorus (P) and potassium (K), which aren’t as variable in the soil as nitrogen (N) is. The more closely you manage NPK, the greater your yield potential.
4. Consider response-to-nitrogen (RTN) scores.
For the last seven years, WinField United has measured RTN scores of various hybrids through our Answer Plot® testing program. A high RTN score indicates the hybrid has an increased chance of a return on investment from applying additional nitrogen, or managing nitrogen for availability later in the growing season. A low RTN score indicates the hybrid has an acceptable yield potential even in situations where nitrogen may be limited. To learn more about specific hybrid RTN scores, visit
Keep fertilizer top-of-mind this season and work with your agronomist to create the best nutrient management plan for your fields. Doing so will help optimize ROI and yield potential, and keep your nitrogen where it should be: in your crop.
1. Raun WR, Johnson GV. Improving nitrogen use efficiency for cereal production. Agron J, 1999, 91:357–363.
With the growing season right around the corner, we’re here to help you with your holistic plant nutrition plan, starting with mitigating stress at planting and understanding your crop’s genetic potential. We’ll continue to explore all aspects of plant nutrition throughout the year right here on the Growing Knowledge blog, so be sure to check back for more plant health tips.
WinField United is a trademark and Answer Plot and WinField are registered trademarks of Winfield Solutions, LLC.

The Truth About Adjuvants

Joel and Kyle
Hosts, WinField United
Joel Wipperfurth is joined by guest host Jon Zuk on this episode of The Deal With Yield. The two cover the main factors farmers should consider when selecting and using adjuvants, including a review of current product testing and best practices for in the tank, in the air and in the plant applications. Plus, Jon teaches us a lesson using spaghetti.
Season 12, Episode 3: The Truth About Adjuvants

The Deal With Yield is a podcast series covering the issues that matter most in crop production.

Boost ROI Potential: Attend a Spray Clinic

Ryan Wolf
Agronomy Services Manager
If you’re looking for ways to make the most of your input dollars this season, look no further. It’s time for another round of Spray Clinics by WinField United, where local experts will be on hand to tackle your toughest questions and provide insights to improve your bottom line.
Farmers and applicators who attend a Spray Clinic find they are more prepared when spray season arrives. Attendees can increase their return on input investment potential because they are trained on the latest application procedures, research and technology. Topics and demos will vary depending on geography, but will likely include:
  • Best application practices – review of new regulations, label requirements, drift management techniques and sprayer cleanout for new and existing technologies
  • Comprehensive weed management planning – developing a robust plan to manage resistant or shifting weed populations using multiple, effective modes of action
  • Optimizing your spray program – choosing the right product, nozzles and rates for each acre; contingency planning and incorporating new products into your program
  • Insights update – new research and field observations that could help improve spray efficacy
  • Equipment enhancements – machinery updates and tools that improve efficiency and spray quality
Spray clinic topics will be tailored to local needs, so each event will be a little different. You’re guaranteed to learn something new this year, even if you’ve attended a Spray Clinic in the past. Our agronomist experts will be available to answer specific questions to ensure you get the most value from your spray program in 2018. You’ll leave with research-backed insights and the latest product information to help you make confident decisions for the coming season.
Spray Clinic locations and dates continue to be added. Contact your local retailer to find out how to participate in an event near you. 

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