In recent years, dogfennel has continued to increase in incidence in turfgrasses. This year, based on observations in the field and questions from turfgrass managers, this weed is continuing to increase. As recent as 5 years ago, dogfennel was only occasionally seen in highly maintained turfgrasses. Currently, I would list dogfennel as one of the more common broadleaf weeds in turfgrasses.
Dogfennel is a perennial weed that, if left unmowed, often reaches 6 feet or more in height. It is a summer weed (summer perennial) that is strongly aromatic when crushed. This is actually one of the identification tools I use. Crush the plant in your hand and smell of it. Dogfennel has a unique smell that is not shared by other weeds in turf. Dogfennel flowers in mid-summer and continues until frost. You can often observe dogfennel in waste areas or along ditchbanks or other undisturbed areas.
Because dogfennel is a perennial, it can be difficult to control. However, in our research trials, we have had excellent control with several products. These include the three- and four-way herbicides that contain 2,4-D and dicamba. We have also had outstanding results with metsulfuron (Manor, Blade, MSM), and products that contain triclopyr (Confront, triclopyr ester, etc).
It is important to treat plants when they are small and actively growing. I get many complaints about lack of control but if this perennial weed is sprayed when small and actively growing, our results have been good with many products.
- MORE ON DOGFENNEL: http://www.turffiles.ncsu.edu/Weeds/Dogfennel.aspx