Conventional weed control methods involve the use of synthetic herbicides, in combination with cultural management practices (S. R. Reitz, personal communication, 2013). In the Pacific Northwest, herbicides with active ingredients such as pendimethalin, oxyfluorfen, and bromoxynil are used to manage weeds in onion crops. For the selective control of grass weeds, growers use Select ®, Fusilade ®, and Poast ® (Prostko, E., Culpepper, A.S., Murphy, T., & McCullough, P., 2009). Outlook ®, Dual Magnum ®, and crop rotation are important tools to control yellow nutsedge (Felix & Ishida, 2009).
Be sure to check herbicide labels and follow label guidelines. Chemical products that are registered for crops change over time and only labeled products should be used.