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Citrus Problems – Leaf Curling

Description

Curling leaves on citrus trees is a very common problem in Hawaii and is most likely caused by the presence of aphids. Broad mites are also mentioned in the CTAHR publication “Citrus For Hawaii’s Yards and Garden,”, but Nick Sakovich, “The Garden Guy” tells me that mites are less of a problem than aphids. If your tree has aphids you should be able to see them on the flowers or leaves. You may also see ants or sooty mold.

Information

Control of aphids

Control the aphids with soap and oil spray. You must also control the ants with an insecticide or ant bait or you will continue to have a problem with aphids because the ants farm the aphids, moving them from leaf to leaf in exchange for the sweet honeydew excreted by the aphids. Do not use a broad spectrum pesticide as you will kill beneficial insects. Ant bait must remain dry to be effective. (No one likes a soggy lunch.)

Soft Bodied Insect Spray Recipe: (controls aphids, mealybugs, whiteflies, scales, citrus black flies)

Begin by preparing a stock solution of Soap-Oil Concentrate:

  • Combine 1 Tablespoon of mild dishwashing liquid (Ivory, Joy or Dr. Bronner’s, NOT ultra formulas like Dawn) with
  • 1 Cup of vegetable oil (peanut, safflower, corn, soybean, sunflower oil)

How to use the Soap-Oil Concentrate:

  • Shake the solution of Soap-Oil Concentrate very well before use
  • Dilute with water by mixing 1-2 teaspoons of concentrate into 1 cup of tap water.
  • Spray plants thoroughly in the morning or late afternoon, especially the undersides of leaves
  • Spray once a week for 2 or 3 weeks to eliminate the insects.

Control of broad mites

Broad mites cause leaf curling by feeding on new growth. They also feed on the rind of the fruit, causing a bronzing effect. You can ignore damage caused by broad mites as this is cosmetic only and does not affect the flavor of the fruit. If you must use pesticide, consult an extension agent.

Kendal Lyon, Hawaii Island Master Gardeners