We all know the importance of mixing different modes of actions in post emerge herbicide programs. One area of corn herbicide management that is easy to neglect is to stay on a consistent rotation of early corn herbicides that are used preplant or preemerge.
We are all creatures of habit and resist change. When we find something that works we tend to stay with that product often too long. Research has shown that not rotating chemicals for three to four years can dramatically change the weed spectrum in a field.
In southeast New Mexico, we are limited in our post emerge programs due to many fields being in a corn to small grain silage continuous rotation. We try to vary our products on the front end of the season. We have found that staying on a strict two-year rotation of early corn herbicides has really helped reduce weed pressure after four to six years. Even if a product is working well, it is rotated after the second year.
We are now able to reduce the post emerge program or just clean up the edges on many fields. We try to rotate three different modes of action in two year cycles and add new chemistry as new products come out, dropping out the older products or ones that share partial chemistry with the others on the list.
Having a long term herbicide chemistry rotation plan could significantly reduce weed pressure over time. Take a look at your plan this winter with your Crop Quest Agronomist as you make decisions for the 2017 cropping season.
Written by: Cort Minor; Roswell, NM