Season long weed control in many vegetable seed crops is a challenge. Most fresh market vegetable crops are grown within 2 to 4 months and soil residual herbicides can be used to control many annual weeds during the entire growing season. Vegetable seed crops, on the other hand, can be in the ground for 8 months or longer. Few soil active herbicides are effective for this length of time. Even if there were herbicides that persist this long, almost nothing is registered for use on these minor acreage, high value crops. Fields that are weed free now can look ugly by May when many of these crops are harvested. An application made now of a soil residual herbicide, will help keep weeds in check until the crop is harvested. After the crop has made seed heads, cultivation equipment is difficult to fit into the field. Growers should anticipate weeds to begin emerging in the spring that will be mature by harvest. Some of the weeds that emerge in the spring, such as clover, are the same size and weight as the crop seed (cole crops) and very difficult to clean out. Hand labor is then the only weed control option. Although few herbicides are registered for vegetable seed production, anything that is registered for use on that crop may be used unless the label specifically excludes use for seed production.

Broccoli for Seed Production

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.