ISU Extension Outlines Pros and Cons of Different Pre-Emergent Herbicide Application Strategies

One benefit to making applications a week before planting is that producers may have a weed-free seedbed come planting time.
One benefit to making applications a week before planting is that producers may have a weed-free seedbed come planting time.

Experts from the Iowa State University Extension and Outreach recently shared their tips for pre-emergent herbicide applications. As they explain, there are pros and cons to different approaches that should be considered before the application process.

Pre-emergent herbicides make up the foundation of herbicide-based weed management systems. However, merely applying pre-emergent herbicides does not always maximize performance, according to the experts. Additionally, limited labor and equipment availability can impact producers who are looking to take this approach.

That said, there are still advantages to making applications seven to 10 days before planting. One benefit is that producers may have a weed-free seedbed come planting time. On the other hand, though, final seedbed preparation tillage can potentially “dilute” the herbicide within the soil profile.

Applications made within a week before or after planting can be beneficial, according to the experts, but if rain doesn’t occur within a week of planting, early-emerging weeds may escape control.

Another option is to make applications more than a week after planting to spread out the workload and extend residual control. However, rainfall also comes into play in this case: it is necessary within a few days of application to activate the product. Herbicide options may also become limited if the crop has emerged before the application process.

For more information on when to apply pre-emergent herbicides to manage weeds, visit the ISU Extension and Outreach website for additional insight.