Check for damage created by midsummer bugs

The next few weeks are a good time to monitor your magnolias for magnolia scale - an insect about the size of a pencil eraser. Typically found on the underside of magnolia branches, scale is responsible for creating an overall thin condition on the tree.

The scale exudes a clear, sticky honeydew after feeding on the plant. Black, sooty mold is a fungus that grows on this honeydew. Gardeners often notice the black mold on or under the magnolia before noticing the actual scale.

The mold itself is not a real problem but a sign that there is an insect problem such as magnolia scale. On small trees, simply pick off the scale and squash them. Other control measures include spraying with summer-weight oil, or applying an insecticide when the scale is in the active crawler stage, generally in early September.

For trees with a history of magnolia scale, a late-winter to early-spring application of dormant oil will provide good control for the scale. If your tree is affected, provide extra water during summer to minimize stress.

• Aphids are showing up in gardens now and typically are not a concern. You will generally find them clustered on new growth at the ends of stems. Look for sticky residue on leaves below the infestation. If the population of aphids is causing more significant damage, try removing them with a stream of water. An insecticidal soap can also be used to kill the aphids.

• Established bluegrass lawns need about an inch of water a week to continue to actively grow and stay green throughout the summer. Water deeply once a week rather than lightly multiple times a week. This promotes a deeper root system so the grass will hold up better to stress.

To determine how long it takes your sprinkler to deliver 1 inch of water, set out a coffee, tuna or other shallow can with straight sides and time how long it takes to fill it with an inch of water. Be consistent with your watering practices. Either water on a regular basis all summer or let your grass go dormant during hot, dry periods.

If your soil is heavy and long periods of watering cause runoff, you may need to split watering into a couple times per week. We had a dry spring, so many lawns have started to go dormant and have started to turn yellow. Mowing your lawn at a height of 3 to 3½ inches or more will also help the grass withstand stress and keep out weeds.

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