Weed of the week: Yellow hawkweed (Hieracium pratense Tausch)

May 22, 2010 in Extension

While driving through Berks County in southeastern Pennsylvania last week, I noticed patches of yellow flowers blooming in many lawns, cemeteries, and other low maintenance turf areas. At first glance these flowers looked like dandelions, but upon closer inspection, I noticed they had all the characteristics of yellow hawkweed.

Yellow hawkweed is common in lawns that are under-fertilized, acidic, and/or droughty. This species is a member of the aster family (Compositae) and has a perennial life cycle, spreading by seeds, rhizomes, and stolons. Bright yellow flowers are produced in clusters of 2 or more on long (6 – 18 inches), hairy, leafless flower stalks during late May and early June (a few weeks after the peak dandelion bloom). Leaves grow in a rosette at the base of flower stalks, and individual leaves are oblanceolate, elliptical, with smooth margins. Leaves and stems are covered with long, coarse, stiff hairs which serve as a good identifying feature of yellow hawkweed.

Yellow hawkweed is easily controlled with commercial broadleaf herbicides containing 2,4-D, MCPP, and dicamba. Control is best achieved when applied to foliage when plants are young and actively growing.