Prefar, Dacthal, Prowl, Treflan, Balan and Kerb are all preemergence herbicides. Only one of these, Kerb, is systemic and moves throughout plant. Because of this, Kerb can be effective in controlling some very small weeds once they have emerged. All of these herbicides are absorbed by roots except for Dacthal, which is absorbed by the shoots. If you have applied one of these and see weeds emerging, don’t give up hope. It is not uncommon for weeds to emerge after a Dacthal application and still die. Kerb can still be applied on very small mustards and grasses (2 to 3 leaves) and be effective without crop injury. All of these kill plants by stopping cell division but they all differ slightly in how and when they should be applied to be most effective and safe to the crop. They were all first registered in the early 1960’s except for Prowl which was registered in 1972.

To contact Barry Tickes go to: btickes@ag.arizona.edu.

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.