5 questions to consider when planning out weed management programs

April 22, 2024 7:00 a.m.

By Bayer Crop Sciences

These questions look at how to develop a weed management plan, the benefits a plan provides, and how a weed management plan can help a farmer make decisions during the growing year.

Q. Why is weed management important?

Because weeds –

  • Compete with crops for the building blocks of yield: water, nutrients, and light.
  • Produce seeds that can germinate the following year or years.
  • Inhibit or slow down harvest.
  • Reduce grain quality when weed seeds contaminate the grain.
  • Can become hosts for crop diseases, such as how Johnsongrass can host maize dwarf mosaic virus.
  • Can host crop-damaging insects, such as chickweed hosting black cutworm.
  • Can be poisonous to humans and/or livestock, like black nightshade.

Q. What is a weed management plan (WMP)?

A WMP is a multifaceted strategy to control weeds based on Integrated Pest Management (IPM) techniques. IPM includes several strategies that approach weed management from several angles. Weed identification, measuring weed populations against economic thresholds, and mapping weeds within a field can help farmers understand the weed pressure in their fields. Using biological controls, crop rotation, tillage, in-crop cultivation, and cover crops can help discourage weed growth. Various herbicide applications, appropriately timing those applications (fall, spring, PRE, POST), and considering the location of the field to be treated in regard to neighboring fields, homes, schools, etc., are also components of a WMP.

Q. Why is it important to have a WMP?

With a WMP in hand, farmers can be mindful of their budgetary constraints and be proactive in their approach to controlling weeds.

Q. What should the basic weed controls be in a WMP plan?

For a basic WMP, consider a fall weed control program (herbicides, cover crops, tillage), starting clean in the spring (residual herbicides or tillage), and in-crop weed management (timely application of residual, foliar systemic, and/or contact herbicides). All herbicide labels should be read and followed, particularly in regard to any potential grazing of cover crops or restrictions regarding future crops.

Q. Should herbicides with multiple sites of action (SOAs) be included in the WMP?

Yes. The use of different site of action (SOA) herbicides can help reduce the potential for weeds to develop herbicide resistance. Different herbicides may be combined during one application or used separately at different times, such as one herbicide applied as a PRE and another applied POST.

TriVolt™ herbicide from Bayer is a PRE option that brings built-in resistance management and consistently high levels of weed control for corn growers. This proprietary combination of Groups 2, 15, and 27 herbicides provides burndown and residual activity for up to 8 weeks through a variety of weather conditions. Following a dry period, Isoxaflutole re-activates with as little as ½ inch of rain and provides continued residual activity. When tank-mixed with Atrazine, TriVolt™ delivers 4 different sites of action to help combat troublesome grass and broadleaf weeds, such as Waterhemp and Palmer Amaranth. 

To hear unfiltered thoughts from farmers about their experiences with Trivolt, visit

Additional References
Wilen, C.A., Koike, S.T., Ploeg, A.T., Tjosvold, S.A., Bethke, J.A., Mathews, D.M., Stapleton, J.J. General methods of weed management, in UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries. UC ANR Publication 3392. Davis, CA.