Arizona Crop Information Site logo
University of Arizona
Vegetable IPM Updates Archive
Cooperative Extension
Hazards from Soil Applied Herbicides to Crops Grown in Rotation (October 30, 2013)
The application pattern and timing of application for the preemergence herbicides used on lettuce are all distinctly different. This is primarily the result of how strongly they adhere to our soils and how safe they are to the crop.

Balan (Benefin) adheres strongly to our finer textured soils and can cause significant crop injury if concentrated near germinating lettuce seed. Label recommendations are to broadcast and incorporate this herbicide prior to listing beds. It is often applied and incorporated to listed beds, however, with acceptable crop safety. It must be mechanically incorporated and crop injury is more likely when using it like this. It is more active on grasses than it is on broadleaf weeds. It is used on fewer acres of lettuce than the other two preemergence lettuce herbicides and is commonly used in combination with one of them.

Prefar (Bensulide), also adheres strongly to fine textured soils but it can
be incorporated with overhead water. The key to getting the most out of Prefar is to incorporate it soon after application with large amounts of sprinkler water. Furrow irrigation does not do an adequate job of incorporation and mechanical incorporation dilutes the herbicide too much. Application by chemigation through sprinklers works well but is sometimes not uniform. Prefar does not control a broad spectrum of weeds and is often used in combination with other herbicides. It controls most small seeded annual grasses and does a good job on purslane and pigweed. It is fair on goosefoot and lambsquarters but is weak on most other broadleaf weeds.

Kerb (Pronamide), differs from the other two because it does not adhere as strongly to the soil. Our trials have demonstrated that if more than 0.75 to 1.0 inch of overhead water is applied, it begins to leach below the shallow weed seeds. To overcome this, delayed and split applications are often made. It also differs from Prefar and Balan by being more systemic in some plants. The other two have only very minimal movement in plants. Kerb can control some seedling weeds that have already emerged. Kerb will also control a broader spectrum of both broadleaf and grass weeds than the other two.
Click picture to listen to Barry video link
To contact Barry Tickes go

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.

Home | Cotton | Veggies | Forages | Grains | Citrus | Crop x Crop
Insects | Diseases| Weeds | Pesticides | Economics | News | Weather | Research | Photos | Contacts | General Info.

Copyright © 2001 University of Arizona,
College of Agriculture and Life Sciences
Webmaster: Al Fournier (