Devrinol (napropamide), herbicide has been used in cole crop production at preemergence for control of many annual grasses and some broadleaf weeds. With the revision of Dacthal (DCPA) some of our PCAs are turning their attention to this tool for weed control. Like many other preemergence herbicides, it works by inhibiting root growth after weed seeds have germinated. It has sometimes injured lettuce when too much was concentrated near the lettuce seed.

Napropamide is a selective systemic herbicide that according to the label limits the growth of grasses in our area such as Barnyard grass, Junglerice, Wild barley, Annual bluegrass, Canarygrass, Foxtail, Goosegrass, Johnsongrass, Wildoats, Sandbur and Sprangletop.
Broadleaves that we have included in the label are: Lambaquarter, Prickly lettuce, Little Mallow, Redroot pigweed, Common and Horse purslane and Sowthistle.
 The PCA study guide for Arizona states that minimum re-cropping intervals of 12 months for cotton, melons and alfalfa, 6 months wheat, 2 for lettuce and 0 for cole crops. We have seen in our trials that head lettuce showed sensitivity to Devrinol when planting too soon.
The following chart from a broccoli trial conducted in 2015 (Tickes/Peña) show the efficacy of napropamide for control of London Rocket and Lambsquarter.