Broccoli and cauliflower seed crops are typically extended into the early summer and can get ugly with summer annual and perennial weeds by harvest time. Some of these weeds have seeds that are the same size and density as cole crop seeds and they can only be removed by costly hand labor. Legumes such as yellow and white sweet clover and volunteer alfalfa can be particularly difficult to remove.
Prowl H2O can be applied from now into February to help keep many of these weeds in check. The rate allowed goes from 1.0 to 2.1 pts. but this is likely not enough. It is safe and more effective at twice this rate. The soil residual activity from higher rates will be twice as long, however, and this may pose an added threat to rotational crops. The label restrictions are from 4 to 12 months for most crops. Although water run applications in the furrows works well, chemigation is not allowed on the label. Applications should be made as a directed spray without getting the product on the foliage. Very high rates over the top of the crop can stunt both broccoli and cauliflower.

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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.