Herbicides for Fencerows and Farmsteads

Every so often, we receive calls about the use of herbicides under fencerows and around various structures on the farmstead (e.g., barns, poultry houses, manure pits, greenhouses, non-grazed fencerows, ditch banks, unpaved lanes, etc.). There are actually numerous products labeled for these utilities. However, when using herbicides around fence lines, it is necessary to know about any grazing or haying restrictions associated with each product. Also, understand what types of weeds (e.g., grasses, broadleaves, woody, etc.) will be controlled by each herbicide and how long soil residual activity can be expected, if at all.

Typical herbicides such as glyphosate, 2,4-D, dicamba, and Crossbow can be used but will likely need to be tank-mixed with each other to provide broad-spectrum control. However, none of these above provide residual activity, so expect to respray after several weeks as new weeds start to invade. Herbicides such as Arsenal, Pramitol, Solicam, Spike, and Rezilon/Esplanade could be mixed with the above products to provide long soil residual activity (few to several months or more) and can control a variety of weeds, but some cannot be used under fences that confine livestock. Refer to Table 2.6-19 in the 2025 Penn State Agronomy Guide for information about these herbicides and others that can be used in these settings. This table lists information about types of weeds each will control, as well as grazing and haying restrictions associated with them.

Another consideration regarding fencerow applications is the amount of total area that will be sprayed and, thus, how much spray solution to mix. For example, if you plan to spray a 1-foot band under the fence or around structures, the distance required to treat one acre equivalent would be 43,560 feet or 8.25 miles. If the spray band is 3 feet wide, then 14,520 feet or 2.75 miles would be required to treat an acre.