The Kerb label specifies that 4 to 6 hours of water should be applied following the Kerb injection to incorporate the herbicide. This practice has worked well but needed to be verified under local conditions. A test was conducted to determine how much post application water is too little for incorporation and how much is too much and will leach the herbicide below the germinating weed seeds. This test contained the following treatments: 0.65lb.a.i./ac of Kerb applied through the sprinklers and followed by 1) no irrigation until the following day, 2) 4 hours of irrigation, 3) 8 hours of irrigation, and 4) 12 hours of irrigation. This test also contained an untreated check. The results are presented in the below graph.

These results demonstrate that shutting the sprinklers off after the Kerb application until the following day, which in this test was 18 hours later, worked very well. Running the sprinklers for 4 hours after application also worked well. The Kerb began to leach and the weed control dropped after 8 hours of sprinkler irrigation. The worst treatment was where the sprinkler had run for 12 hours after application

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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.