Dog Fennel in Pastures and Hay Fields

The Extension office has received a lot of calls about dog fennel in pastures and hay fields this year. Dog fennel is part of the aster family and is easily identified by its height and feathery leaves. Technically, it is considered toxic but animals rarely eat it. Dog fennel often grows in areas with low soil fertility or in overgrazed pastures; therefore, rotational grazing and adding soil amendments per soil test are important in reducing this weed. It has a fibrous root system which makes it almost impossible to pull up.

Mowing when dog fennel is blooming can help control it. This method will take several years. It typically blooms in late fall and has very tiny white blooms. The top of the plant will have a white hue to it – that is the time to mow it. Herbicides can work to control it, but early season application when the plant is immature will be more effective. A combination of 2,4-D and Dicamba will provide some control when the plant is less than 10 inches. After that height, Crossbow, Remedy Ultra, or PastureGard HL will likely be the better choices. Don’t spray during a drought; the stress will reduce the efficacy. Read and Follow herbicide labels. The label is the law.