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Michele Warmund
University of Missouri
Plant Science & Technology
(573) 882-9632
warmundm@missouri.edu

Mitigation of Herbicide Injury with Windbreaks

Michele Warmund
University of Missouri
(573) 882-9632
warmundm@missouri.edu

August 1, 2022

minute read

One of the challenges to field production of specialty crops has been plant injury due to the off-target movement of herbicides, such as dicamba and 2,4-D. Other than growing plants in protective structures or planting crops and cultivars that are less susceptible to herbicide injury, there are few short-term solutions to avoid plant damage when herbicides drift onto your property.

For long-term mitigation of herbicide drift injury, you may want to consider erecting a permanent fence of wood or some other material, such as heavy-duty woven landscape fabric or construction-grade geotextile fabric. A fence constructed from these materials can be quickly erected, but can be relatively expensive for large properties and may only protect low-growing vegetables and small fruit plants.

Another solution for drift mitigation on farms is a living windbreak, using closely-spaced plants on the perimeter of the property. Sorghum-sudangrass is an annual plant that grows 5 to 12 feet tall. Multiple rows of this crop can provide an inexpensive annual barrier for protection against herbicide drift on low-growing crops. Sorghum-sudangrass is usually planted after May 1st or when the soil temperature is above 60°F in Missouri.

Another option is a multiple-row windbreak consisting of perennial trees and shrubs. In a 3-row windbreak, one row of evergreen trees, a second row of shrubs, and a third staggered row of shrubs, in a planting about 40 to 50 feet-wide will provide greater protection against herbicide drift than one with fewer rows. However, even a single row of tall plants with dense foliage will help minimize damage.

Spruce windbreak with additional red-stemmed dogwoods planted along its edge with a pasture

A multi-row windbreak consisting of conifers and densely-growing deciduous shrubs.

When choosing plant materials, consider their suitability to the climate, soil, capacity for fast growth, and potential height and density. Also, avoid windbreak plants that harbor pests that can harm your specialty crop. Shrubs may be planted 3 to 8 ft apart in a row; small, thicket-forming trees about 8 to 15 feet apart; and large conifers 25 to 30 feet apart. Alternatively, trees and shrubs can be planted at closer spacings, and later when they become crowded, every other one can be removed. In either situation, plants should be spaced closer together than those in a home landscape, since any gaps in the windbreak become funnels that concentrate wind flow and accelerate wind speed.

Some of the trees and shrubs that are suitable for this type of windbreak include American plum, silky or red twig dogwood, witch hazel, ninebark, and American filbert. Shortleaf loblolly pine is a fast-growing evergreen that is also recommended. Eastern red cedar and arborvitae are two other evergreens that may be used in windbreaks at some sites. Nurseries that specialize in native trees and shrubs offer these plants, but orders must be placed at least 6 months in advance to ensure availability.

In Missouri, the prevailing winds are from the north and northwest, but drift can be multi-directional and auxin herbicides are known to move from great distances. Therefore, it's best to plant a windbreak that will enclose the property or planting, if possible. Some of the drawbacks to windbreaks of trees and shrubs are that it takes more than one growing season to produce a solid wall of vegetation to mitigate drift. Secondly, purchasing trees and shrubs of any size is expensive.

There are government programs available to help purchase and maintain windbreaks for drift mitigation on farm property. The first step in the application process is to obtain a farm and tract number from your local Farm Service Agency. Next, visit your local Natural Resources Conservation Service Office (NRCS) to apply for funding from the Environmental Quality Incentives Program, or EQUIP program. In addition to the EQIP application, a conservation plan is required.

These documents usually have a fall deadline, but early submissions are encouraged. Funding is competitive and applications are ranked by priority. Under the EQIP program, growers usually pay upfront costs with their own funds and are reimbursed after the windbreak is certified as meeting NRCS standards. However, a participant can opt for the advance payment option. NRCS offices are staffed with personnel who can assist with the application process and windbreak planning.


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REVISED: August 1, 2022