Wasps, hornets are beneficial pollinators
Populations of yellow jackets (yellow-bodied social wasps) build up in summer. They are particularly attracted to sweet things like soda. Practicing good sanitation is the best way to minimize pest problems.
The wasps tend to make their nests in the ground, in piles of brush or in stone walls, so watch these areas as you are working in the garden. When the weather is warm during the day, there can be a lot of activity with the yellow jackets flying in and out of the nest.
Bald-faced hornets construct large paper nests in trees and large shrubs at head height and above, so look in the tree canopies as you work in the garden.
Paper wasps build nests under eaves, signs and fence railings and will sting if disturbed.
These all are beneficial insects, so control them only if they pose a safety hazard. Wasps are considered beneficial because they assist in pollination by feeding on nectar, and they control pest insect populations by feeding them to their larvae.
• Holes in the lawn dug by raccoons and skunks may indicate the presence of grubs, which feed on grass roots. Check for areas of the lawn that are browning or where the grass lifts like a piece of sod.
If there are more than 12 grubs per square foot and you see extensive damage, you may consider using a product designed for quick kill of the grubs. Be sure to read the bag carefully to ensure you are buying the right chemical for grub control at this time of year. It is important to follow the instructions for application.
• Some crabapples are very susceptible to apple scab and those not treated in spring may have lost many of their leaves. Their remaining leaves can be affected with black and yellow spots. The wet weather last spring was conducive to this disease so it is prevalent this year.
Spraying now will not help combat this disease but you can give the trees extra care by supplemental watering as needed for the remainder of this year and fertilizing in fall or next spring. Remove all infected leaves and do not add them to your compost pile. Also, consider replacing disease-prone trees with a cultivar that is resistant.
• Hawthorns with a more severe case of cedar apple rust may have foliage that turns bright yellow and drops prematurely. Small yellow spots will appear on leaves after infection in spring. This disease requires eastern red cedar (Juniperus virginiana) as an alternate host, so avoid planting this plant if you have hawthorns in your garden.
As with crabapples, spraying now will not help your trees, since controls need to be applied in spring to prevent these diseases.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.