Given that harvest is finally wrapping up for many, attention is shifting to other fall tasks on the farm. You may wonder if there is still time to try fall spraying or cover crops this fall given their benefits for weed control or soil health. The answer is that it still should be worth giving both a try, even with the delayed harvest and colder temperatures we have had this fall.
Fall spraying is an excellent way to deal with winter annual weeds such as marestail. With harvest delayed this year and freezing temperatures at night you may think that fall spraying is done for the year, however, winter annual weeds are amazingly resilient to freezing temperatures and are still green and actively growing in most fields.
The challenge with the cooler temperatures is that adsorption and translocation of herbicides is going to be slower, possibly leading to reduced control. Temperatures below 40 degrees are going to slow control, especially with systemic products like glyphosate, so growth regulator options like 2,4-D and dicamba may perform better. However, if you have fields with heavy winter annual pressure, especially marestail, the benefits of even partial control are going to be beneficial next spring.
To maximize your chances of control, watch the forecast and look for windows of two to three days with slightly higher temperatures and sunshine, use a full rate of adjuvant, and use a spray volume of 15 gallons per acre or greater for better coverage.
With cover crops, the options this time of year are limited to either rye, wheat or triticale, with rye being the best option. This time of year, you may or may not see the cover crop emerge this fall, although rye will germinate at soil temperatures as low as 34 degrees. Even if you don’t see fall emergence, typically these late seeding dates still emerge fine next spring as soon as soils warm. This is often earlier than field conditions would allow for you to get in to seed a spring cover such as oats.
As with any late planting scenario, increasing your seeding rate is beneficial to help ensure a stand and get better results. Also, remember that we don’t have to see lots of top growth to get benefits from cover crops, the root growth that we can’t see has lots of benefits for our soils.
One excellent spot to try cover crops is if you are doing any dirt work on waterways or ditches. The disk or blade is a great eraser at making our flow areas look better, but remember that without something growing to hold the soil in place, the same rill or gully erosion is going to occur.
So to recap, if you are interested in trying some fall spraying or cover crops, you should have some time to try and cover some acres before winter settles in, just be sure to manage your expectations compared to earlier dates. I’ve seen both of these operations going on the last few days, so you wouldn’t be alone in trying them.