David M. Kopec, Extension Turfgrass Specialist
Many homeowners wonder about why they have weeds in their lawn in the winter? You'll hear most about this from homeowners in the low desert regions who do not overseed their lawns (brown bermuda) or from those at high elevations where it is cold enough to discolor bluegrass, fescue and ryegrass lawns. In these cases, the lawns are "off color" and the weeds tend to show up nicely.
For effective weed control, the proper identification of the weed is essential. Weeds that show up in most lawns this time of year are as follows.
Low Elevation Bermuda Lawns
Winter Annuals
Brome grass (grass) Mediterranean or six week Schismus (grass)
Annual bluegrass (grass) Burrclover (broadleaf)
Mustard (broadleaf) Sheperds purse (broadleaf)
Wild celery (broadleaf) Cheesweed/mallow (broadleaf)
Perennials (more active in winter)
Oxalis/creeping charlie (broadleaf) Dandelion (broadleaf)
White clover (broadleaf) Various thistles (broadleaf)
High Elevation Lawns (Kentucky bluegrass, fescues, ryegrass)
Winter Annuals
Bromegrass (grass) Black medic (broadleaf)
Annual bluegrass (grass) Chickweed (broadleaf)
Perennials
Clovers (broadleaf) Henbit (broadleaf)
Dandelions (broadleaf) Plantains (broadleaf)
Thistles (broadleaf) Fescues-in bluegrass lawns (grass)
Oxalis/wood sorrel (broadleaf)
Weed Control
Grassy weeds can be controlled with Round-up or Finale in dormant bermudagrass at low elevations. However, it will be slow to work. Grass control at high elevations areas will be even slower using Round-up or Finale. Spot spray the weeds only. Broadleaf weeds can be sprayed with 2,4-D containing products or mixtures with other phenoxy-type products which include 2,4-DB, mecoprop, and or DICAMBA. For those who wish to remove brodleafs by cultivation or hand pulling, either irrigate the lawn or pull them right after a rain. Weeds like plantains, mustards and even young thistles are easily pulled out when the ground is wet! Annual bluegrass is controlled with selective acting post herbicides, but these are not available for the homeowner.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.