Iowa: Finish Up Fall Weed Management

This week is a welcome break from the fall chill, and it is a great opportunity to finish up any final fall weed management in pastures and no-till crop fields. Ideally, herbicide applications should be made when the sun is shining and daytime temperatures are above 50-55 degrees Fahrenheit. With high temperatures this week in the upper 60s and low 70s across much of the state, it’s a great time to complete this work.

 

The horsenettle (left) is in poor shape to treat with a herbicide, but the bull thistle (right) is healthy and easier to treat in the fall.
While this horsenettle (left) is in poor shape to treat
this late in the fall, the bull thistle (right) is healthy a
nd easier to treat in the fall than other times of the year. 
Image credits: Meaghan Anderson.

 

Earlier frosts have eliminated most annual weeds, but winter annual weeds and more troublesome biennials and perennials are preparing for winter by moving energy reserves belowground.



Systemic herbicides will be more readily translocated to those belowground plant structures to provide more consistent control of these weeds than at other times of the year. Before spraying, closely examine fields to confirm the presence and health of target weeds. Check the resources below for more information on fall weed management in different scenarios.

Source URL: https://crops.extension.iastate.edu/blog/bob-hartzler-meaghan-anderson-rebecca-vittetoe/time-finish-fall-weed-management