Difficult Summer Weeds
Wild violet, is a cool season, perennial, broadleaf weed. It is one of the first plants to flower in spring, growing well during cool parts of the growing season, and is usually found in shaded, moist areas. The heart-shaped leaves have scalloped edges with a waxy coating.
The waxy coating on violet leaves tend to repel weed control materials, with little chemical being taken in by the plant. Violets tend to be resistant to most herbicides but are most susceptible in the spring while they are flower.
Controlling wild violets in a lawn or landscape can be a difficult challenge, and will certainly require more than one herbicide application before it is accomplished. As with any lawn weed, the best control practice is to promote a dense and healthy turf through soil testing to mointor pH, proper mowing, fertilizing and irrigation.
Creeping woodsorrel is a spreading perennial weed with a reddish-purple color that frequently roots at the nodes. The three heart-shaped leaves of creeping woodsorrel is nearly identical to yellow woodsorrel. Creeping woodsorrel is most commonly introduced to the landscape through nursery container-grown landscape plants. Once transplanted and established it will quickly escaped the landscape beds and invade the surrounding turf. Established creeping woodsorrel is difficult to manage and control because it is also resistant to most weed control products.
Japanese Stilt Grass, or Nepalese Browntop, is a pale green annual plant that grows up to 3 1/2 feet in height. The leaves are asymmetrical and lanced-shaped with a distinctive midrib and range from 1 to 3 inches long. Late summer yields flowers, and soon after fruits mature on the plant. It is found mostly in shady locations in moist or dry soil. It can be pulled from moist soil or mowed in late summer before the seeds are produced. The best way to control Japanese Stiltgrass is with very early spring pre-emergence herbicides. It can also be managed in the summer with certain post-emergence herbicides that are labeled for the control of summer annual grassy weeds.
Mark Schlossberg is the President of ProLawnPlus in Baltimore, MD. He graduated from the University of Maryland in 1977 with a B.S. in agronomy. He is the President of the Maryland Association of Green Industries, and past president of the Maryland Turfgrass Council.