Save ash trees or replace them?
Damage caused by the emerald ash borer infestation is becoming very visible in the Chicago area, with many dead and dying trees in home gardens and woodlands and along roadsides.
This insect attacks all species of ash trees and will kill them in time. It is important to remove dead trees promptly, because the wood will dry out quickly and cause the trees to become hazards.
If you want to try to save your ash trees, contact a professional arborist to determine if it is too late to begin a treatment program with an insecticide. The treatments will need to be repeated indefinitely every one to two years, depending on the product you use.
Otherwise, replace your ash tree with a different type of shade tree. I chose to remove the ash trees in my home garden and replace them with other tree species.
Trees planted in lawns can benefit from a ring of mulch in an even layer around the trunk to reduce competition with grass roots and keep mowers and weed whips from damaging the bark of the trunk.
If the tree is small, mulch out to the drip line (as far as the branches reach). If this is not feasible, make the layer of mulch as wide as you can. Even a 6-inch-wide mulch ring will help protect tree trunks from serious damage by power tools.
Do not mound mulch or soil around trunks. It is unattractive and can cause rotting at the base of the tree.
Groom the plants in your borders to improve their appearance and maximize flower production. Deadhead - prune off spent flowers - on your annuals and perennials to encourage them to continue flowering. Remove yellow foliage to keep the plants neat and tidy.
Gently remove dried or yellowed bulb foliage, since the bulbs are going dormant and have already stored nutrients for next year's flowers.
Be sure to pull out any garlic mustard that may be flowering in your garden. Garlic mustard has a pungent garlicky odor and bears clusters of small white flowers. Hand-pulling is effective as long as you pull up the entire root.
This plant has a two-year life cycle. Seeds germinate in early spring. They remain low for the first year and can literally carpet the ground. In the second year, the now mature plants can reach up to 4 feet tall and bloom May through June. Numerous small white flowers will be clustered at the ends of stems and may also be found at points along the stem where leaves are attached.
Garlic mustard dies after flowering. In August, the long slender seed pods open, releasing numerous seeds that allow the plant to spread readily.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.