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All About Gardening and Gardening Q & A by Pernell Gerver |
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"Identifying and Controlling Insects and Diseases" |
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Whether you're growing perennials, annuals, bulbs, roses, trees, shrubs, lawn, fruits, vegetables, herbs, or house plants, it's a fact of life there are insects and diseases that cause damage to plants. Here in western Massachusetts we have our fair share of both insects and diseases. Insects and diseases in our area range from the fairly innocuous to those that pose a severe threat to plants. Insect pests that cause damage to perennials, annuals, and bulbs include thrip, nematode, cutworm, slug, snail, Japanese beetle and other beetles, red lily leaf beetle, leafminer, mite, fourlined plant bug, aphid, caterpillar, ant, leaf hopper, whitefly, spittlebug, earwig, weevil, nematode, iris borer, and grasshopper. Roses are bothered by many insects including aphid, thrip, beetle, caterpillar, mite, leaf hopper, and scale. Trees and shrubs have their share of insect pests that cause serious damage including borer, hemlock woolly adelgid, mite, beetle, caterpillar, aphid, scale, lacebug, leaf hopper, plant bug, thrip, mealybug, whitefly, weevil, leafminer, leaf roller, sawfly, psyllid, midge, and nematode. |
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The lawn comes under attack by many insect pests including grub, sod webworm, chinch bug, and ant. Insects that bother fruits include borer, psyllid, scale, aphid, ant, caterpillar, beetle, mite, fruit fly, nematode, apple maggot, curculio (a type of weevil), and leaf roller. There are many insect pests that attack vegetables and herbs including tomato hornworm, striped cucumber beetle, spotted cucumber beetle, imported cabbage worm, cabbage looper, European corn borer, corn earworm, carrot rust fly, squash vine borer, squash bug, Mexican bean beetle, Colorado potato beetle, asparagus beetle, nematode, cutworm, whitefly, flea beetle, slug, snail, earwig, grasshopper, mite, leafminer, caterpillar, beetle, leaf hopper, aphid, pillbug, cabbage maggot, onion maggot, thrip, and wireworm. Insect pests that bother house plants include mealybug, whitefly, aphid, scale, spider mite, fungus gnat, and thrip. There are many different types of plant diseases, but some of the most common and damaging ones here in western Massachusetts include powdery mildew, rust, and early blight. Powdery mildew is probably one of the most prevalent plant diseases. It affects all different types of plants both in the garden as well as indoors on house plants. Powdery mildew forms a white, powdery coating on plants' leaves and stems. It's a fungus that is spread by rain, watering, and even wind. The spores overwinter in the soil and splash up onto the lower parts of plants when it rains or while watering. The disease spreads up the plant, coating the leaves and stems. It often causes the leaves to drop off the plant. In the garden, powdery mildew can attack just about any plant, but it's most often found on rose, lilac, monarda, tall garden phlox, aster, wax begonia, dahlia, squash, and zinnia. Powdery mildew also affects house plants including begonia, African violet, streptocarpus, and kalanchoe. Rust is another fungal disease that is a serious problem of many garden plants. It causes small, round, rust-colored or brown spots that appear on the undersides of leaves as well as on plant stems. Leaves become dry and die. The disease weakens the plant and causes its growth to be stunted. Plants with severe infections can die. Rust spores overwinter in plant debris as well as on trees. Infection begins in spring as the days become warmer, but nights remain cool. Rust spreads from plant to plant during wet weather. Leaves that remain wet for long periods of time are susceptible. The spores are also spread by wind and can travel many miles to infect healthy plants. Rust attacks rose, zinnia, hollyhock, geranium, annual aster, chrysanthemum, dianthus, iris, fuchsia, sunflower, cedar, fruit trees, grape, birch, mountain ash, asparagus, and bean. Early blight is also a fungal disease that causes severe damage, especially to tomato plants. It begins as small, irregular brown spots on the leaves. The brown spots have many concentric rings in the center. The spots have a yellow outer edge and when there are numerous spots on a leaf, the entire leaf can turn yellow. Once the entire leaf is affected, it drops off. The disease starts on the lower leaves and eventually makes its way up the plant, even spotting the fruit. The disease is at its worst as the fruit is maturing. In severe cases, it causes most to all of the leaves to drop, weakening the plant. It also reduces the size of the fruit and leaves the fruit susceptible to sunscald since there's no foliage left to shield it from the sun. Spores of early blight overwinter in plant debris and are most active during humid, warm weather. In addition to tomato, early blight also affects pepper, celery, and potato. Fortunately, there are effective, organic treatments for just about every insect or disease that affects plants. Depending on what the problem is, gardening products I'll use include Neem Oil, Milky Spore Powder Grub Control, and Diatomaceous Earth. Click on a product name to read more about it and order it from Pernell Gerver's Online Store. |
by
Pernell Gerver
Pernell
Gerver, Horticultural Communication Services All rights reserved.