This is Aaron Nygren, your local agronomist with Nebraska Extension in Colfax, Cuming, and Stanton counties. Hope everyone is making some progress in the field this week after the long weather delay. As you harvest, be sure to be looking for fields with winter annual weeds and make plans for control. Many of the fields I’ve been in have healthy populations of a variety of winter annual weeds such as marestail, henbit, chickweed and pennycress (For a good resource on identifying winter annual weeds, refert to EC304 below).
For control of these weeds, your best option is going to be fall spraying. Even with the late harvest, we can still have plenty of time for fall herbicide applications if the weather cooperates. Good control is likely as long as daytime air temperatures remain above 50 degrees and weeds are actively growing. However, control is possible even when conditions are cooler. Every year it seems like we learn that we can go later into fall than you would expect and still have good control, as I’ve jokingly heard industry reps say to keep spraying as long as there isn’t ice forming on the booms…
Some advantages of fall spraying are:
- Fall applications target the most vulnerable stage of growth for winter annuals
- Temperatures are typically warmer in the fall compared to the spring, leading to better herbicide activity.
- Even weeds not completely killed by herbicides are more likely to winter kill
There are lots of products labeled for fall application, with many different price points. One of the cheaper options is to go with an application containing 2,-4D ester and/or dicamba which will do a good job on most broadleaf winter annuals but offers little to no residual activity. If you do want some residual, there are many other products that may offer control all into the spring, potentially reducing the need for a spring burndown application. If you have had issues with downy brome or chickweed, one option is including glyphosate for better control. For a list of herbicide options and expected application costs, refer to EC130, Guide for Weed, Disease, and Insect Management in Nebraska, which will have efficacy tables such as the one below.
Fall Burndown Herbicides from EC130
If you are planning on using cover crops for weed control and don’t have them planted yet, this year could be challenging. Given the delayed harvest and plentiful rain, winter annual weeds already have a head start in growth so don’t expect a late planted cover crop to provide 100% control.
In summary, prioritize fields for winter annual control as you harvest, and use fall spraying to give good control, even if you have to have it custom applied given the shortage of labor during harvest.
To listen to this radio message again or to get more information, visit our local website at croptechcafe.org or give me a call at 352-3821. This is Aaron Nygren, your local agronomist for Nebraska Extension on KTIC radio.
