From the Help Desk – Weed Control in the Fall

QUESTION

Client requested identification and control recommendations for a weed in the lawn and in ornamental beds.

DIAGNOSIS / RECOMMENDATION

The specific weed is oxalis (yellow wood sorrel).  This is not the proper time of year for effective control, but weeds can always be pulled and discarded.  This particular weed is a perennial, blooming throughout much of the season (Ref 1).

Different approaches are needed for control of this weed in lawns and in ornamental beds.  For lawns consider a spring application of broadleaf herbicide once weeds are up; also soil test and manage turf properly. In ornamental beds, control pre-emergence or post-emergence. Watch to be sure ornamentals are listed to avoid injury. (Per current Pest Management Guide recommendations for lawns and for ornamentals).

ADDITIONAL INFORMATION

This time of year, various weeds can become problematic.  The first line of defense again weeds in lawns is to ensure healthy turf.  And that always starts with soil testing.  But September through November is a good time to work on fertilizing the lawn according to test results, as well as overseeding with recommended varieties (Ref 2).  In lawns, while it is possible to pull some weeds, it may be more effective to consider properly selected, properly timed use of herbicides (Ref 3).  However, using an herbicide on large weeds or when the weed will die out naturally in a few weeks is not a recommended approach.  Keeping the lawn healthy throughout the season includes proper mowing height and fertilization, as well as being aware of water needs will help keep weeds to a minimum in the lawn (Ref 4).  For weeds in ornamental beds and vegetable gardens, mechanical control (pulling or hoeing) often is the most effective approach and can be used any time of year.  Proper use of mulches also can help minimize weed issues (Ref 5).

RESOURCE LINKS

Article by Betsy Brown, Bedford Extension Master Gardener Volunteer; Help Desk Coordinator