By Dwight Lingenfelter
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, understanding what types of weeds (e.g., grasses, broadleaves, woody, etc.) will be controlled by each herbicide and how long of 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 broadspectrum control. Also, 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 Esplanade provide long soil residual activity (few to several months or more) and can control a variety of weeds, however, some cannot be used under fences that confine livestock. Refer to Table 2.6-19 in the Penn State Agronomy Guide for information about these herbicides and others that can be used in these settings.
Source : psu.edu