Neglected lawns ease the spread of crabgrass

Crabgrass may be evident in your lawn now, especially if it has been neglected. This annual weedy grass seeds readily in the fall.

Keep your lawn closely cut to prevent crabgrass seed formation or pull it out by hand. There are herbicides that will control crabgrass, but they are not as effective after the crabgrass has set seed.

Make note of bad areas in your lawn and apply a pre-emergent herbicide (one that prevents weed seeds from germinating) in early spring before lilacs flower.

• It is time to protect the trunks of smooth-barked trees like young maples from deer rubs, especially if you live near a forest preserve or other forested area.

Deer rub their antlers on trees and prefer the trunks of smooth-barked trees. This can damage the bark and even kill trees if the damage goes all the way around the trunk. Wrap trunks with hardware cloth, chicken wire or plastic snow fencing to a height of 5 feet to help protect the tree. This protection can be removed in early spring.

Paper tree wrap does not always provide adequate protection against buck rubs.

• Powdery mildew (a disease that causes a grayish, powdery film on leaves) is present now. Common plants that can get powdery mildew are lilacs, phlox, bee balm, zinnias and nannyberry viburnum.

This disease typically occurs in the late summer when the weather is warm and humid. Fungicides can help control powdery mildew if applied before the infection becomes severe. In most cases, there is no need to apply any controls for powdery mildew at this time of year.

Other options include selecting more mildew-resistant varieties, or moving the infected plants to an area of the garden that has better air circulation.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.