Integrated Pest Management

Powdery mildew is a fungal disease that attacks many different plants. Check your gardens, paying special attention to dogwoods, beebalm, phlox, lilacs, and, of course, your roses. Look for a white powdery film on the leaves and flower buds, curled leaves, and stunted growth. This disease thrives when rain is lacking and is spread by the wind. Humid conditions favor powdery mildew, but liquid water kills the spores. You can spray plants daily with water in early morning to prevent powdery mildew. Be sure to provide plants with good air circulation and remove badly infected leaves. If perennials are severely damaged it’s a good idea to cut them back. Horticultural oil controls powdery mildew on a variety of plants. A mixture of one gallon water, one tablespoon baking soda, and a quarter teaspoon dishwashing liquid sprayed every five to seven days also works well as a treatment or a preventive measure.

Fall webworms attack a wide range of deciduous trees and shrubs. Look for webs at the tips of branches that shelter large groups of caterpillars. Mature larvae are about one inch long, hairy, and green-yellow in color with black dots. They feed together and never leave the web. As more food is required the web is expanded. The caterpillars may feed for four to six weeks. Prune out any webs and dispose of them. Bacillus thuringiensis can be used on young fall webworms that are less than one half inch long.

Now is the time to check your pines for pine sawflies. Look for masses of one-inch-long larvae that are yellow-green with black dots. Sawflies begin feeding on the tip of a branch and strip one branch before moving on to another. In only a matter of days small pines can be completely defoliated. Because the damage takes place in a short period of time, it is important to check your pines carefully every couple of days. Since they feed together in groups, it is easy to remove the larvae by hand. If the infestation is severe you can spray them with horticultural oil. You may have begun to notice lacebug stippling on your azaleas. It is too late to do any treatment this year, but begin looking for nymphs early next spring. Repeated infestations can contribute to the death of your plants especially if they are growing in full sun.

If hot, dry weather persists, stop watering your lawn and let it go dormant. This will help it avoid diseases during this stressful period. Once temperatures cool down a bit and rain returns, your lawn will perk back up. Check birches, oaks, and hornbeams for yellownecked caterpillars. They are yellow and black with a yellow-orange band around the neck area; when disturbed, they elevate their heads in a defensive posture. They can completely defoliate a tree in days, but because the damage occurs late in the season it isn’t as harmful to the tree as it might appear. Yellownecked caterpillars feed in groups so it is easy to remove them by hand.

Plant lettuce, spinach, and other salad greens after mid-August. Summer heat and drought has taken its toll on slugs, and fall plantings are less likely to be damaged by these slimy molluscs. Most salad greens bolt in response to high night temperatures and long days; the shorter days and cooler nights of late summer prevent bolting. Greens may be harvested as late as early December if the weather is mild.

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