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1997, No. 5
Controlling White Clover
White clover (Trifolium repens) has been a common weed problem throughout much of the 1997 growing season.
This weed occurs in most turf areas and especially in moist, low-fertility soils.
White clover was formerly a common component of turf mixes due to its relationship with nitrogen-fixing bacteria.
It is still available in mixes or by itself and may be useful in low management turf areas.
It has the ability to persist at short mowing heights and can attract bees to turf areas.
Description
White clover is a cool season perennial member of the Legume family (Fabaceae) that reproduces primarily by seeds and occasionally creeping stems that can root at the nodes.
It will form patches in turf and emerges from a fibrous root system.
The compound leaves are composed of three unstalked oval leaflets, up to 4/5 inch long.
They are dark green and often with faint, white, crescent-shaped markings.
White clover inflorescences occur in ball-shaped, white-to-pink clusters of pea-shaped flowers that are held slightly above the foliage.
The inflorescences are up to 1-1/4 inch in diameter, composed of 40 to 100 flowers, and appear from May to September.
Postemergence Control of White Clover Using Broadleaf Herbicides During Autumn
White clover, along with cool season annual and other cool season perennial broadleaf weeds, can be controlled during the autumn growing season using applications of postemergence broadleaf herbicides.
Be sure that weeds are actively growing before applying a postemergence broadleaf herbicide; drought stress, in particular, can dramatically reduce control.
Both amine- and ester-formulated products are available.
Ester-formulated broadleaf herbicides are best used during this weed control period.
While ester-formulated products may be more effective at controlling broadleaf weeds than amine-formulated products, they are also more prone to volatilization than amine-formulated herbicides, particularly as temperatures rise.
Never tank mix amine- and ester-formulated broadleaf herbicides.
In research conducted over a five-year period at the University of Illinois, several herbicides have provided effective postemergence control of white clover.
These herbicides are 2, 4-D + MCPP + dicamba; triclopyr + clopyralid; and 2, 4-D + triclopyr.
Weed-control products containing clopyralid have been particularly effective on white clover.
For additional information regarding other chemical weed controls, see Chapter One of the 1997 Illinois Commercial Landscape and Turf Pest Management Handbook.
When using any chemical pest control, be sure to read, understand, and follow the label directions for proper use of these chemicals.
If mishandled or misapplied, postemergence broadleaf herbicides may damage or kill desirable ornamental or edible plants in the landscape.
(Tom Voigt, Bruce Branham, and Tom Fermanian)
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