Typical lawn weeds in Ohio include grass or grass-like weeds and broadleaf. Grass weeds form narrow, upright leaves with parallel veins. Broadleaf weeds develop wide leaves with net-like veins. Annual weeds compete with permanent lawn grass and reduce density. Perennial weeds present more of a challenge to control once they are established because their creeping stems contain buds that produce new growth.
Weeds are managed more effectively while they are in the sapling or juvenile stages, according to North Central Region Cooperative Extension Service's Common Weed Seedlings of the North Central States.
Crab grass is one of the most common lawn weeds in Ohio, and as the name implies, it belongs to the grass family, Gramineae. The spring annual forms a clump in thin areas of the yard and spreads by shallow roots. The coarse, textured leaves turn purple, then die in the fall after releasing their seed.
Look for spiked flower heads to emerge from the center of the clump in mid-July. The flower heads bear large quantities of seed that germinate the next spring if left unchecked. Treat crabgrass before it germinates with a pre-emergent herbicide.
Dandelion takes its name from the French phrase Dent de lion, or lion's tooth, and it belongs to the Compositae family. The perennial grows in thin spots of the lawn and those that have been cut too short. Dandelion's broad, jagged leaves often blend with the grass until a bright, yellow bloom appears on its milk-storing stem. Get rid of the weed by clipping the root, the plant's energy store. The weed rushes to recover the lost growth and taps energy from the root in the process. Continued clipping exhausts the plant's energy.
Canada thistle is not native to Ohio, but it is naturalized in 58 of the state's 88 counties, according to the Ohio Biennial and Perennial Weed Guide. Like dandelion, Canada thistle belongs to Compositae, which means that it is not a true grass or grass-like weed, but a broadleaf. This prickly leaved plant spreads by a creeping root system and seed. Each lavender flower holds up to 5,000 seeds. Apply a selective herbicide designed for broadleaf weeds to eliminate Canada thistle.
Three members of the Setaria family grow in Ohio: giant foxtail, green foxtail and yellow foxtail. The seed head of all three annual varieties looks like the tail of a fox, but each type demonstrates different characteristics. Giant foxtail forms leaves with many small hairs on the leaf blades and the seed head tends to droop when mature. Green foxtail produces smooth leaf blades and the seed head remains only loosely erect. Yellow foxtail possesses long, wiry hair, where the leaf blade and sheath meet. The seed head stands erect. The stem flattens out and the base develops a reddish-brown color.