CONTROLLING VIOLETS IN THE LAWN
The common blue violet (Viola papilionacea) is one of the first flowers to bloom in spring. Many people enjoy seeing them in shady wooded areas where they form carpets of purple accented by heart-shaped green leaves. Also known as "meadow violet," this perennial becomes troublesome when plants move from their natural habitat to landscaped areas or a lawn.
This species of violet is normally found in damp woods, meadows and along roadsides. Colonies establish easily in shady to partly sunny locations and once established are able to tolerate drought. Fleshy rhizomes (underground storage organs) allow these violets to withstand periods of stress.
The meadow violet forms a basal rosette of smooth green heart-shaped leaves. This species spreads by several means: short, stout, branching rhizomes, seeds from blossoms, and cleistogamous flowers (unopened underground flowers that are self-pollinated). Flowers have five petals and are borne on leafless stalks. They bloom from early spring through June. Fruit pods have a three-valved capsule and tiny dark brown seeds.
The meadow violet is difficult to suppress, but an herbicide containing triclopyr can reduce populations in a lawn. Triclopyr is absorbed by leaves and roots and is readily translocated throughout the plant. Because triclopyr is a broad leaf herbicide, it cannot be sprayed or allowed to drift onto plants other than lawns. This herbicide is labeled for turf grass use; when applied according to label specifications it should not affect an established lawn.
The best time to spray herbicides on perennial weeds is September through early October when plants are storing carbohydrates for winter and the following spring. No significant response may be seen in fall, but results should be apparent in spring. Do not apply herbicide when rain is expected within 24 hours, or preferably 48 hours. Read the label and caution information before applying any herbicide.
A healthy lawn is the strongest defense against weeds. Maintaining a regime of proper mowing, watering, and fertilization will enable any gardener to combat weeds in a lawn. Contact the Yard and Garden Line or your local county Extension Office for information on lawn maintenance and fertilization. You can also visit Extension's website, then click onto Horticulture and Gardening. Extension's URL is: http://www.extension.umn.edu