By Barry Tickes, UA Area Agriculture Agent

Almost all herbicides used on lettuce, cole crops, and melons have restrictions on how soon wheat can be planted in rotation after use. Experience has demonstrated that safe intervals can vary considerably based upon many factors and are almost always much longer than they need to be.

The most important factors are the rate applied, irrigation practices, and tillage. For example, when the herbicide Kerb was banded at two to four pounds per acre after planting and incorporated with furrow irrigation, it was common to see treated strips across the wheat fields which followed. This is uncommon now with lower rates that are chemigated.

We still see some Balan injury at the ends of fields or in overlaps especially when Sudangrass is planted. Wheat is not very sensitive to Prefar and carryover injury is uncommon.

Contact Tickes: (928) 580-9902 or btickes@ag.arizona.edu.