Heavy damage may be done to garden plants at this time of the year by lace bugs, spider mites and aphids. They feed mostly by sucking juices from the undersides of leaves. Better check your plants to see if they are infested and need some help.
Lace bugs feed on azaleas, Pieris japonica (andromeda) and pyracantha. Injured foliage becomes stippled and mottled with grayish blotches. Yellowed leaves may drop from the plants, resulting in dieback of twigs and small branches.
Adults are about one-eighth of an inch long, the nymphs (young) range from less than 1/32 inch to near adult size.
Azaleas growing in full sun are much more likely to be attacked than those in shade. When serious infestation occurs among evergreen varieties such as Hinodegiri and Kaempferi, all of the foliage may appear light gray to whitish.
There are several generations of lace bugs a year and large plants can be almost ruined in a season.
Specialists recommend spraying with Sevin for lace bug control. Directions on the label should be followed closely. Be sure to treat the underside of the leaves because that is where they mostly feed.
Spider mites are tiny creatures, hard to see without a lens. Heavy infestations cause leaves to turn pale or yellowish. Badly infested plants usually have a fine cobwebby appearance on the leaves, particularly on the underside where they feed.
They attack a wide variety of plants including tomatoes, beans, eggplants, peppers, roses, ivy, spruce, arborvitae, marigolds and petunias. During hot weather they multiply rapidly.
Use of sevin to control insects in the vegetable garden favors mites as much as the hot weather. It kills predators of mites allowing them to increase even faster.
There are several kinds of mites and Kelthane appears to be effective for most kinds. Directions on the label should be followed closely.
A high-pressure nozzle on the end of a water hose can provide fair control of mites. Spray the foliage once a week with the water under pressure. On large evergreens, spray with the water as high as you can reach.
Aphids secrete a sticky substance called honeydew. When they are feeding on a tree, honeydew may cover everything under it. Fungi feed on honeydew and cause a sooty mold to form.
When the honeydew starts to drip, lady bird beetles and syrphid flies usually move in to feed on the aphids. Pretty soon they provide fairly good control. When insecticides are used, such as malathion or spectracide, aphids and predators are killed. The aphids build up again very quickly but not the beneficial insects.
If roses, chrysanthemums and other plants become infested with aphids, spray only the plants that need it badly. To spray as a protective act is likely to do harm and little good.