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IPM
Due to concerns about health, the environment, and pesticide resistance, pest control practices once taken for granted are now under scrutiny. Regular preventive pesticide applications are often unnecessary. Healthy plants can usually defend against or tolerate pest attacks. Natural controls, such as beneficial insects and birds, can often suppress undesirable insects making the preventive and indiscriminate use of pesticides imprudent. Spraying broad spectrum pesticides kills insect pests as well as beneficial insects resulting in increased plant damage due to the loss of beneficial insects.
Pesticide Resistance: after repeated applications of a certain pesticide, pests may adapt to the chemical and are no longer harmed by it. These pests that survive then breed and pass the resistance genes to their offspring. Integrated Pest Management: a sustainable approach to managing pests by combining biological, cultural, physical, and chemical tools in a way that minimizes economic, health, and environmental risks.
A better approach to managing pests is Integrated Pest Management (IPM) — which emphasizes using a combination of environmentally friendly methods that focus on preventing pest problems.
Basic Building Blocks of IPM
- IPM begins at planting time, with pest-free and pest-resistant plants and a landscape design that encourages natural controls.
- Keeping your plants healthy is the best defense against pests.
- Regular scouting, or keeping an eye on your yard’s plants, helps detect pest problems early, before significant damage occurs.
- Plants with aesthetic damage don’t necessarily need to be treated with pesticides. Consider the amount of aesthetic damage you are willing to accept.
- If you see a pest outbreak, determine if a problem really exists or if natural enemies are already present and are working on your behalf.
- If pest control proves necessary, try the safest alternatives first, such as handpicking insects or pruning infected parts of a plant. If pesticides become necessary, choose the least harmful materials. The “softest” insecticides on beneficial insects and other non-target organisms (people, pets, and wildlife) include insecticidal soap, horticultural oil, and microbials (e.g., spinosad, abamectin, Bacillus thuringiensis ‘Kurstaki’).
- Pesticides should only be used to spot-treat affected plants or lawn, not in blanket applications.
Spot-treatment: application of a pesticide to the problem plant or area, rather than a blanket application or “wall-to-wall” coverage. AVOIDING PEST PROBLEMS
The way that you design and maintain your yard either establishes a barrier against pests or throws out the welcome mat for them.Follow These Tips to Prevent Pests:
- Think before you plant. Each time you place a plant in a spot that’s not ideal, you will likely have to protect it from pests. Plants in unfavorable growing conditions (compacted soil, inappropriate pH or light, competition with weeds, etc.) are targets for pests.
- Choose insect and disease resistant plant varieties.
- Go easy on water and fertilizer. Too much can cause excessive growth, making plants vulnerable to some insects and diseases. Encourage healthy growth by applying fertilizer and water only when needed and in moderate amounts.
- Mowing grass too short and severely pruning trees and shrubs weakens them, inviting pests. Mow to the proper height and prune selectively.
- Use barriers to block pest entry.
- Encourage beneficial insects by choosing some plants that provide the nectar needed by adults and by minimizing the use of broad-spectrum pesticides.
IDENTIFYING PEST PROBLEMS
Inspecting plants helps identify pest problems early, before they get out of hand. You can give plants the once-over anytime you water by hand, mow, or are tending to other outdoor chores. If you need to scout more than once every week or two you’ve planted the wrong plants. If you know key pests for certain plants and when to expect to see them it will make scouting much easier.Common plant pests in Alabama include aphids, mealybugs, scales, whiteflies, thrips, plant-feeding mites, and caterpillars. Often you will spot evidence of a pest’s activity before you see the insect itself. If you see curled, rolled or deformed leaves, mold on leaves or stems, ants scurrying up and down plant stems or discolored “trails” on leaves, you are likely to find a pest lurking somewhere.
Detecting small insects and mites can be difficult. One method that works well is to flick the leaves of small branches against a sheet of white paper. Use a magnifying glass to search for movement or evidence of pests.
Look on the branches and on the upper and undersides of leaves for pests such as scales and immature whiteflies. Sooty mold on leaves is a telltale clue to an infestation by what are known as piercing-sucking insects. Aphids are one example. These pests pierce the plant with sharp mouthparts and suck the sap. Some piercing-sucking insects secrete a sugary substance called honeydew, on which the black-colored sooty mold fungus feeds and grows. Sooty mold doesn’t injure a plant directly, but it does block sunlight from leaves, reducing photosynthesis and making plants unsightly. Ants also signal the potential presence of pests. Ants feed on honeydew and often protect the insects that produce it.
Photosynthesis: the process that turns light energy into chemical energy in green plants. There are also instances where chewing damage can be seen but the causal agent is not present. In these cases it is good to check back during the night. Many chewing plant feeders like snails, slugs, and some beetles and caterpillars are active at night. You may also see plant damage but few pests indicating that beneficial insects are already taking care of the problem. These may include ladybugs and their larvae, lacewings and their larvae, assassin bugs, spiders, parasitic wasps, and parasitic flies (syrphid or hoverfly larvae and tachinid flies).
Accept some insect damage on plants. No one can maintain a complete insect and disease-free landscape, and a little damage will not hurt your plants. Remember, in order to have the “good guys,” such as ladybugs, there must be some “bad guys,” or pests, for them to feed on. If a pest problem persists, take a sample of the damaged plant and pest to your Extension office for identification and suggestions on how to proceed in using IPM techniques.
TREATING PEST PROBLEMS
What do you do when you have a pest infestation or a disease outbreak? IPM focuses on using chemicals as a last resort. IPM methods form a first line of defense to deal with problems.
- When pest populations are high, you can often reduce or eliminate the problem simply by removing the affected leaves or plant parts. Crush, burn or compost these infested plant parts to prevent the disease or insect from spreading.
- For large, slow-moving pests, picking insects off by hand can often defeat the problem. Dispose of any captured insects so they do not return to feed again.
- Avoid using broad-spectrum pesticides. They are not selective and kill insects that are not problematic. Safe alternatives to traditional pesticides include insecticidal soaps and horticultural oils, both of which work to reduce populations of sucking insects. Products containing an extract of the bacterium Bacillus thuringiensis ‘Kurstaki’ take care of caterpillars.
- Always treat for specific pests, and only treat the affected plant.
- Read all product labels carefully and follow them accordingly. Remember that the label is the law! Do not attempt to mix your own chemicals or apply homemade recipes unless you have been properly trained to do so.
It is usually best to apply soaps, oils, and other pesticides during the cooler part of the day to avoid injuring plants. Do not apply before a rainstorm or in windy conditions, which may end up getting more pesticide on you instead of the plant. Do not apply insecticides when bees are foraging. Wait until after sundown to spray plants where bees have been foraging. Pay attention to warnings on insecticide labels regarding hazards to bees. Always read the label to find out if any plants are listed as being sensitive to the product. To determine if the product will hurt your plants, apply it to a small portion of a leaf first, and check for leaf burn after 1-2 days. Phytotoxicity often looks like a burn on the edge of leaves.
Phytotoxicity: degree to which a chemical is toxic to (injures) plants; plant sensitivity to a particular chemical, application rate and environmental conditions influence degree of damage that may result from chemical treatment. TREATING COMMON LANDSCAPE PESTS AND THEIR MANAGEMENT
Ants: Ants have three body segments and range in size from 1/16"-1/2", depending on species. Most species are not harmful. In the landscape, they do not affect plants but the bite and sting of fire ants and carpenter ants affects people. When ants are present, you may observe mounds, ants in trails and on plants. Ants may also signify the presence of aphids or other honeydew producing insects.
- Natural enemies: Phorid flies (decapitate fire ants), Thelohania fire ant disease.
- Other controls: Bait effectively controls fire ants. Be sure the material is dry and fresh. Apply in late afternoon or evening around edges of mound. Do not apply when ground or grass is wet. Do not disturb mound. Store baits in a cool and dry environment.
Aphids: Aphids can be winged or wingless with pear-shaped bodies that may be green, yellow, black, red, or multi-colored. They are typically found feeding on new growth. Damaged leaves appear yellow, twisted, or distorted; ants or sooty mold may also be present. A strong stream of water can knock off most aphids giving beneficial organisms a chance to control the infestation.
- Natural enemies: ladybug adults and larvae, lacewing larvae, syrphid fly larvae, parasitic wasps.
- Other controls: Prune infested plant parts. Apply insecticidal soaps or horticultural oils. You can also apply a soil drench with a product containing imidacloprid.
Caterpillars: Caterpillars are the larvae of butterflies and moths. They chew on foliage, which creates skeletonized or notched leaves. You may also see greenish fecal pellets on leaves or below plants.
- Natural enemies: Wasps, predatory stink bugs, big-eyed bugs, birds, lizards.
- Other controls: Remove by hand (use pliers to remove stinging caterpillars), apply Bacillus thuringiensis ‘Kurstaki’ (most effective when caterpillars are small).
Chinch Bugs: Adult chinch bugs are 1/5" long and black with white patches on wings. Young nymphs are smaller, reddish, and have a white stripe across their backs. Chinch bugs feed on St. Augustinegrass, often in stressed areas in full sun or near pavement. Injured turf yellows and dies.
- Natural enemies: Big-eyed bugs, earwigs, and parasitic wasps.
- Other controls: Avoid high fertilizer rates. Maintain St. Augustinegrass at height of 3" in sun and 4" in shade. Use chinch bug-resistant grass varieties when available. Spot-treat infestations with insecticides labeled for chinch bugs.
Mealybugs: Mealybugs are soft-bodied insects that are 1/16"-1/8" long with well-developed legs. Their bodies and egg masses are covered by a powdery white wax. Mealybugs attack leaves, twigs, and roots and leave behind white, mealy wax deposits. They can often be found in the leaf axils. Sooty mold or ants may also be present.
- Natural enemies: Ladybugs, lacewing larvae.
- Other controls: Spray with horticultural oil or insecticidal soap. If that fails, apply a systemic insecticide (i.e., imidacloprid) to the root system. Soil drench systemics may take several weeks to work. Choose a product that affects only pests that feed on plant sap.
Leaf axils: where the leaf attaches to the stem. Systemic insecticides: are commonly applied as a soil drench but can be spray applied. These insecticides are taken up by the plant and move in the plant through sap. Insects with piercing-sucking mouthparts are infected when they feed on the treated plants.
Mole Crickets: Mole crickets are velvety brown, 1½" long, and feed on turfgrass and vegetable roots. They have flattened front legs adapted for burrowing. Mole crickets affect all grasses, but prefer bahiagrass and bermudagrass. Injured turf may be spongy and thinning, with ¾"-round holes that are signs of tunneling. Infestation usually occurs in the same area each year. You can test for infestation by flushing the area with soapy water (1-2 tablespoons soap in a gallon of water). Mole crickets will surface within 3-5 minutes if they are present.
- Natural enemies: Parasitic wasp, red-eyed fly, insect-parasitic nematodes, and birds.
- Other controls: For chronic infestation, consider replacing turf with trees, shrubs or groundcovers. If necessary, spot-treat infestations in May or June with insecticides labeled for mole cricket control.
Plant-Feeding Mites: Mites are so small that they may not be visible to the naked eye. They are about 1/32" and may be red, yellow, or green with oval bodies. They may also have spots. Some spin loose webs on foliage. Mites reproduce rapidly in hot weather resulting in large populations. Injuries to plants look like light-colored dots, giving leaves a dull, gray-green, speckled appearance. Some mites live and feed in the growing tips resulting in distorted new growth. Other mites cause plants to form galls which are abnormal ball-like swellings of plant tissue.
- Natural enemies: Ladybugs and predatory mites.
- Other controls: Flush with water, and then alternate with soap and oils if necessary.
Scales:Scales can vary in size, shape and color, but are, for the most part, approximately 1/8" in diameter. Soft scales and armored scales are the most common. Soft scales produce honeydew (sugary secretion). The armored scale body is hidden under a waxy scale covering. Mature scales are stationary and feed on leaves, twigs, stems, and fruit. Watch for feeding damage resulting in yellow spots on top of leaves with the scale underneath. Ants or sooty mold may also be present. “Crawlers” are the immatures and are the easiest to control because they are the most vulnerable.
- Natural enemies: Ladybugs, parasitic wasps.
- Other controls: Scrape scales off plant tissue. See other controls for mealybugs.
Thrips:Thrips are approximately 1/32" winged insects that scar leaves, buds, and flower petals to drink sap from wounds. Injured plants may be dull gray with curling, distorted leaves.
- Natural enemies: Predaceous thrips, predatory mites.
- Other controls: Apply horticultural oils, insecticidal soaps, spinosad spray.
Whiteflies:Adult whiteflies look like tiny white moths on plants. They take flight when leaves are disturbed. Eggs are on leaf undersides. Nymphs are oval, flat, transparent-to-greenish in color, and may look like scales. They are stationary and are located on undersides of leaves. Ants or sooty mold may be present.
- Natural enemies: Fungi (most effective in humid weather), parasitic wasps, ladybugs.
- Other controls: Spray with insecticidal soap. Follow with horticultural oils or soil drenches with insecticides containing imidacloprid, if necessary. Be aware that several species are resistant to insecticides.
WHAT ABOUT PLANT DISEASES?
Many organisms, including viruses, fungi and bacteria, can cause diseases in plants. Diseases can be quite specific in the plant species they commonly attack, but identifying diseases can still be extremely difficult. Home gardeners often mistake environmental damage or maintenance problems for diseases. For example, Spanish moss, lichens, and ball moss are not parasites that should be killed or removed; they are merely plants themselves. Another common misdiagnosis in coastal areas is mistaking saltwater damage for disease. Irrigating plants with salty well water can cause yellowing around the edges of leaves and leaf-drop starting from the bottom part of the plant’s canopy.When a plant does have a disease, the problem may be merely cosmetic rather than truly damaging to the plant. Examples are minor leaf spots or other damage to select leaves. Such minor aesthetic concerns are no cause for alarm or treatment. There are serious diseases, however, that can damage or kill plants they affect. Examples are mushroom root rot on woody ornamentals, fire blight on pears, and brown patch on turf. Such diseases can seriously damage the plant’s appearance or yield.
Because diseases are difficult to identify, do not assume a disease is the culprit just because of a plant’s appearance. Use a magnifying glass to look for insect pests that may be causing the damage. Also analyze maintenance practices for causes related to visible symptoms. If you still suspect a disease, contact your county’s Extension office for advice on how to collect and submit plant samples for disease diagnosis and recommendations on the least-toxic methods of treatment.
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