Tuesday, July 27, 2021


Master gardener’s corner: Aphids


Gerry hernandez | glhernandez@ucanr.edu

Almost every plant has one or more aphid species that occasionally feed on it. Although aphids can curl leaves and produce stick honeydew, they rarely kill plants. When aphid numbers are high, natural enemies frequently feed on them. When pesticides are necessary, use less toxic products.

Aphids are common in your garden because:

Aphids like lush new growth. Don’t over fertilize.

Aphids build up on flowering plums, roses, tulip trees, crape myrtles, apples, and many vegetables. Expect aphids when you grow these plants.

Ants protect aphids from their natural enemies. Keep ants off plants.

To reduce aphids:

Prune out infested leaves and stems.

Knock aphids off plants by shaking the plant or spraying a strong stream of water.

Protect seedlings with covers.

Wait for hot weather; most aphids are heat-intolerant.

Protect aphids’ natural enemies:

Lady bugs (larvae and adults), lacewings, syrphid fly larvae, soldier beetles and parasitic mini-wasps.

Beneficial insects will come into your garden naturally when aphids are abundant. Protect these good bugs by avoiding the use of insecticides that can be toxic to a broad variety of insects.

If insecticides seem necessary, use the safest products:

Use nonchemical pest control methods first.

Insecticidal oils and soaps are the safest products. When properly used, these will solve most insect problems.

Oils and soaps work by smothering aphids, so apply thoroughly.

Soaps and oils are best for vegetables and roses. For larger trees such as crepe myrtle use a narrow range horticultural oil.

Systemic insecticides can kill bees and beneficial insects.

Rose plants get a lot of aphids in the spring. My tip is to squish them. I get great satisfaction squeezing the aphids between my fingers.■

-—For more information go to: ipm.ucanr.edu

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