Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
There is some overlap of herbicide options for snap beans and lima beans, but growers need to pay particular attention that a product is labeled for snaps or lima beans and do not assume if it is labeled for one, it is labeled for both. One thing that is consistent for both lima and snap beans is that postemergence herbicides need to be applied to small weed seedlings (3 inches tall or less).
Weed control in snap beans starts with a good soil-applied program. The regional recommendations include Eptam, Treflan or Prowl, applied pre-plant incorporated; Dual, which can be applied preemergence or pre-plant incorporated; or Command or Sandea applied preemergence. Early postemergence treatments for broadleaf weeds include Basagran, Reflex, or Sandea. Select Max, Targa/Assure II, or Poast are labeled for postemergence grass control. UD research has seen consistent control with Dual used at planting followed by a timely (1 to 2 trifoliate stage of the beans) application of Reflex and Basagran. If there are concerns about timely application of the postemergence herbicides, consider use of a broadleaf weed herbicide at planting.
The biggest difference from snap bean herbicides is Reflex. Snap beans tolerate Reflex quite well, but lima beans are very sensitive to Reflex. In fact, Reflex applied earlier in the season then lima beans planted as a second crop can also result in lima bean injury. A soil-applied herbicide program for lima beans is very important due to the lack of effective postemergence herbicides. Herbicides listed in the regional vegetable guide for lima beans include:
Pre-plant incorporated: Prowl or Treflan
Pre-plant incorporated or preemergence: Dual or Pursuit
Preemergence only: Sandea or Spartan Charge (only labeled in DE)
Postemergence: Basagran or Raptor for broadleaf weeds; Select Max or Poast for grasses.