July 22, 1992
This summer many gardeners have been puzzled by the sudden wilting and death of tomato plants. Possible causes of wilting include lack of water, vascular wilts, tomato spotted wilt virus, walnut toxicity, or stalk borers.Lack of Water
Now is the time to be observant about the location of developing wasp nests around the house. Social wasps including paper wasps, yellowjackets and hornets have selected their summer-long nesting sites by now and are busily enlarging nests and raising offspring to increase colony size. Left unchecked, these social wasps will produce colonies of up to several hundred individuals by the end of the summer. Our solitary wasps such as the cicada killers and mud daubers are also active now.
White clover and birds-foot trefoil have been prominent plants in some Iowa lawns this spring and summer. Both are valuable agricultural crops. They have become common in many lawns because they are prolific seed producers and adapt well to mowing and other lawn care practices.
White clover (Trifolium repens) is a creeping perennial. The stems root at the nodes where they touch the soil. The leaves are composed of 3 leaflets. Plants bloom profusely in early summer. Flower heads consist of 20 to 40 individual white to pinkish-white, fragrant flowers.
Several excellent cutting flowers are now in bloom or soon will be. Cut flowers will last longer if cut in the morning when they are most turgid. Use a sharp knife or scissors to cut the stems from the plant. Dull scissors may crush the flower stems and make it impossible to absorb water. Many flower arrangers will recut the stems at an angle before putting them in a vase or arrangement. Remove any foliage that will be under the water line. If left on the stem, the foliage will rot and discolor the water in the container.
Iowa was very fortunate for over two decades in that we had no substantial establishment of gypsy moth in spite of the ease with which this pest migrates on cars, trucks, buses, recreational vehicles and interstate merchandise shipments. It at first appeared our luck had changed with a large introduction of gypsy moth egg masses on infested nursery stock last spring, but, as the following update, based on information provided by Dr. Catherine Thompson, an Entomologist with the Iowa Department of Agriculture and Land Stewardship indicates, the situation is not as bad as it could have been.