Aphid Control and Prevention

Plants are facing constant threats from pests and pathogens. Nearly half of the one million known insect species feed on plants, including aphids. These insects are phloem-feeders that belong to the family Aphididae and order Hemiptera. Over 4000 aphid species have been described and a number of these are known to damage plant health. Aphids are major economic pests that cause yield losses worldwide, especially in temperate regions. Damage to plants as a result of aphid infestation can result in water stress, reduced plant growth, wilting, and importantly, these insects can are vectors of economically important plant viruses.1

North America is home to more than 1,300 species of aphids. Some of them target only one type of plant; others are less particular. They also attack the grass. Your clues that they've arrived: The grass blades turn yellow-orange and grow poorly, and ant hills suddenly appear. Mow your loawn, and spray it with aphid control pesticide. Aphids can be almost any color, but they're all tiny (less than 1/10 inch long), pear-shaped, and usually wingless, with soft bodies and mouths that can pierce right through even the toughest leaves and stems. Aphids are famous for the honeydew they produce (sweet, sticky stuff that ants love so much).

In the cold regions, aphids hatch in May and June from eggs laid the previous fall. Then the female gives birth to live nymphs every 2 weeks until the weather turns cold. Some nymphs born late in the summer grow wings as they mature. Then they fly to trees and lay eggs that overwinter in the bark and hatch the following spring.

Aphid Facts

  • Suck the juices from plants, leaving them wilted, discolored and stunned.
  • Often spread viruses
  • Produce a sweet, sticky honeydew that attracts ants
  • Reproduce prolifically as long as the weather stays mild

This fragrant mix will halt an aphid invasion fast. It'll also kill any foul fungi that might be lingering on your plants:
1 tbsp. of Garlic Oil
3 drops of dishwashing liquid
1 qt. of water

Mix these ingredients together in a blender, and pour the solution into a hand-held sprayer. Then take aim and fire. Within seconds, those bugs'll be all history.

Garlic Oil

Keep a batch of this potent oil in the fridge, and you'll always have ammunition against aphids and other garden thugs.
1 bulb of garlic, minced
1 cup of vegetable oil

Mix the minced garlic and the oil, and pour into a glass jar with a tight lid. Put the jar in the refrigerator and "steep" the oil for a day or two. Then strain out the solids, and pour the oil into a fresh jar with a lid. Keep it in the fridge and use it in any cases that call for Garlic oil.

Aphid nymphs
Aphid nymphs (Click to zoom in)

Control Tips

  • To control them use the garlic spray
  • In early stages, dislodge them with a blast of water
  • Spread aluminum foil shiny side up, on the ground under your plants. The reflected light will scare the daylights out of aphids.

Aphids can't stand bananas. Just lay the peels on the ground under your plants, and aphids will keep their distance. As an added bonus, these skins will break down fast and enrich the soil with valuable potassium and phosphorus. Like many insects, aphids are drawn to the color yellow. Hang yellow sticky traps on your plants

Go Easy on the Nitrogen

[Picture of black aphid]

Black Aphid

A plant that is getting too much nitrogen is a magnet for aphids and other sucking insects. In particular, avoid synthetic/chemical fertilizers, which deliver nutrients directly to the plant's roots in highly concentrated form. Instead, use a natural/organic fertilizer, which adds essential nutrients to the soil, where they become available to the plants as they need them. Encourage Predators Like Ladybugs and Lacewings. Aphids love nasturtiums and marigolds, but they hate other plants with equal passion. Include plenty of these winners in your garden: Basil, catnip, fennel, garlic, mint

Other Options

Hot Pepper Spray - Chop or grind hot peppers into fine particles. Mix the ground-up peppers with water, then strain out the particles to form a clear solution. Spray twice, 2 to 3 days apart. Make sure contact is made with the aphids.

Oxalic Acid. Found in spinsch and rhubarb leaves, oxalic acid is poisonous in high concentrations. Mix a simple rhubarb spray by first cutting up 1 pound of leaves and boiling them in 1 quart of water for 30 minutes. Strain and bottle the liquid. To help it stick to the leaves, add a touch of soap, not detergent.

Tomato-Leaf Spray - Tomato-Leaf spray may also kill aphids. Pack 1 quart of leaves into a crock or bucket; pour 1 quart of boiling water over them. Let steep 1 hour, then strain through a cloth, squeezing leaves to extract as much liquid as possible. Refrigerate in a capped jar until needed. Before using dilute with a gallon of water.

Sticky Trap - If these cover a large enough area, sticky traps can be used as control devices for aphids. Bright yellow pannels about 10 by 10 inches in size should be coated with sticky material such as TackTrap, motor oil, or petroleum jelly. Place traps adjacent to, not above, susceptible plants. Do not leave these traps out for more than 3 or 4 weeks, or beneficial insects, as well as pests, may be traped.

Botanical Poisons - Neem. Purchase a commercial neem product and mix it according to label instructions. Apply the spray to aphid-infested plants twice, at weekly or longer intervals, until pests are under control. Spray carefully to thoroughly cover all plant parts. The spray will be most effective if you apply it in early morning or late afternoon. Neem is generally fairly harmless to beneficial insects, but it may have an effect with repeated use. Save it for use against serious infestations, when milder measures don't work.

Pyrethrum. Apply pyrethrum directly to aphids in a spray form. Coat the undersides of the leaves as well as the tops. Two applications are recommended, 3 to 4 days apart. Remember, pyrethrum also harms beneficial insects, so use it only as a last resort.

Steps to Prevent Aphids

The fall garden cleanup is the best way to prevent aphid problems. Get rid of aphids overwintering as eggs on bark and garden litter. As soon as you harvest each crop, remove all old plants and overgrown weeds, leaving soil completely bare. Cultivate soil 6 to 8 inches deep, using a hand tool or a rotary tiller. About 2 to 3 weeks later, cultivate just 2 inches deep. In early spring, about 2 weeks before planting give the garden another 2 inch cultivation, and cultivate again at planting time.

There are a number of preventive sprays you can use to reduce aphid numbers early in the season: horticultural oil spray, insecticidal soap, seaweed spray, etc. Don't spray much past a month after last frost, or you will be killing a lot of beneficial insects.

Some gardeners recommend interplanting vegetables with chives, garlic, mints, onions, and petunias to repel aphids. Anise, coriander, nasturtiums, penny-royal, petunias, and southernwood are mentioned for controlling aphids in the orchard. Some clover species support parasites of wooly apple aphid.

Animal Predators - Chickadees, nuthatches, purple finches, warblers, chipping sparrows, and toads are some of the common aphid eaters.

Phloem-feeding insects are among the most devastating pests worldwide, not only because of the direct damage caused by feeding, but also because of the viruses that many of them transmit. Most phloem-feeding insects are able to transmit more than a 100 different plant viruses. At present, the main way to control phloem-feeding insects is via the frequent use of insecticides, which is only partly successful and hazardous to the environment. A better solution would be the use of plant varieties that are resistant to the insect.

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