Gardening News: Managing pesky summer lawn weeds
By Debra Levey Larson
Media/Communications Specialist, University of Illinois College of Agricultural, Consumer and Environmental Sciences
URBANA, Ill. — Some weeds in the lawn, such as creeping Charlie and white clover, seem almost impossible to control. University of Illinois Extension offers some tips to give you a fighting chance.
“Creeping Charlie, also called ground ivy, is a mint that forms large mats and is incredibly invasive,” said Rhonda Ferree, U of I Extension educator in horticulture. “It creeps on stems that can grow up to 2-1/2 feet long. The leaves are round to somewhat kidney shaped, with round, toothed margins, and small funnel-shaped purplish-blue flowers from April to June. Ground ivy is typically more of a problem in shaded sites with poorly-drained, fertile soils, although it can spread to sunny locations.”
Ferree explained that white clover, like ground ivy, grows from seed and creeping stems.
“White clover was formerly a common component of turf mixes, due to its ability to fix nitrogen,” she said. “It is most commonly found in moist, low-fertility soils. The leaves are a typical three-part clover, and it has white ball-shaped flowers from May to September.”
To manage these weeds, and other broadleaves in the lawn, Ferree recommends trying a combination of chemical and non-chemical management options.
“First, find out why the weeds are there,” she said. “Some weeds are indicators of soil problems. For example, ground ivy prefers shady, wet areas, so one management option is to alter the problem area by reducing shade and soil moisture.”
Another non-chemical technique is to make sure your lawn is healthy and competitive.
“Healthy, full grass will out-compete most types of weeds,” Ferree said. “In turf areas, maintain turf density and health through proper lawn care practices, such as proper selection and establishment, watering, mowing, fertilization and related practices.
“Pulling the weeds by hand is one option, but be sure to get as much of the plant and root system as possible,” she said. “Pull up every stem you see and destroy them; do not put them into the compost. Continue routing out the difficult weeds once a month all summer, and again the following year.”
But, in the end, chemical control may be necessary. Ferree warns that weeds must be actively growing for the herbicide to work, so they must be applied in mid-spring to early summer and/or mid-to late autumn. A treatment in mid-summer will not work. For the lawn, use a product containing a combination of two or more products: 2,4-D, mecoprop or MCPP, or dicamba. Difficult weeds, such as ground ivy and white clover, often need more than just 2,4-D in the tank mix.
Ferree cautioned that the chemical products she listed should only be used in turf areas. “They will damage or kill many desirable ornamentals or edible plants in the landscape, and those applications are illegal,” she said.
For more information about controlling weeds in the lawn or other garden areas, contact the local Extension office by visiting www.extension.illinois.edu. Ferree welcomes questions on her Facebook page at www.facebook.com/ferree.horticulture.
From the Aug. 3-9, 2011, issue