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Apple, pear, narrow-leaf plantain, and dock.
Leaves - Tightly curled on spur growth and at base of shoots (Fig. 1); usually much honeydew present within the curled leaf and on adjacent lower leaves. The aphids do not hide under a cottony wax-like covering and do not attack twigs or branches like woolly apple aphids.
|Figure 1. Rosy apple aphid damage to apple leaves. (H. Philip)|
Branches - Young shoots twisted and deformed.
Fruit - Small and deformed near infested leaves; Jonagold fruit especially sensitive to aphid feeding (dimpled fruit surface with green spots throughout flesh) (Fig. 2).
|Figure 2. Jonagold apples damaged by rosy apple aphid feeding. (BCMA)|
Egg - Dark greenish to shiny black, oval.
Nymph and adult - Pink to purplish, up to 2 mm long, coated with a very fine white powder-like covering. Some adults have wings (Fig. 3).
|Figure 3. Rosy apple aphid colony. (BCMA)|
Rosy apple aphid overwinters as eggs on 2-year-old or older wood. Eggs hatch when buds open in the spring. After several generations, winged adults migrate to plantain for the summer. Winged adults return to apple in the fall where they lay overwintering eggs.
Carefully examine 10 leaves or bud clusters per tree on 10 standard trees per block or 5 clusters per tree on 20 dwarf trees per block, beginning at tight cluster or early pink stage.
Rosy apple aphids are attacked by several insect predators and parasites that can aid in control of this pest if not harmed by toxic chemicals.
See chemical control of apple aphid. Control may be necessary if aphids are present on 10 of 100 bud or fruit clusters in a 100-cluster sample and few predators are present. Summer sprays will also control other aphids. Assail and Admire will also control leafhoppers.
Recommended control timing and products include:
15 mm green to tight cluster – Closer plus dormant oil.
Summer – Alias, Admire, Assail, Cygon or Lagon (non-bearing only), Beleaf, Clutch, Closer, Exirel, Sivanto Prime, Malathion, Movento or TwinGuard. Research shows that chloronicotine products such as Alias, Assail and Admire are toxic to mite predators and may cause an increase in mite populations. Do not apply more than two applications of Alias, Assail or Admire either alone or alternately per season regardless of target pest (codling moth, aphids, leafhoppers, leafminers) to avoid possible mite flare-up. Assail applied when codling moth is laying eggs or larvae are hatching will aid in codling moth control.