Ministry of Agriculture and Lands
Tree Fruit Aphids
Apple Aphid
Hosts
Apple and pear.Damage
Leaves - Terminal leaves are curled downward and sticky with honeydew secreted by the aphids.Fruit - Honeydew may drip onto the fruit causing russet spots and promote growth of black sooty mold.
Shoots - Highly infested shoots of young trees are stunted or malformed.
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Apple aphids |
Identification
Egg - Oval, shiny black.Immature - Dark green with black legs, wingless.
Adult - Yellowish-green to light green, winged or wingless.
Life History
The apple aphid overwinters in the egg stage on water sprouts and terminals. Eggs tend to be concentrated on a few trees in a planting. Hatching begins as apple buds open in spring. Aphids feed on flower parts and then move to growing shoots. Females produce many generations during the summer and disperse throughout the orchard and to other orchards. Males appear in the fall and mate with the females that then lay overwintering eggs.Monitoring
Infestations on the terminal 7-10 leaves of 50% of shoots of mature trees in a block can cause fruit damage. Inspect young bearing and non-bearing trees for increasing aphid populations and restricted tree growth.Control
Cultural - Avoiding excessive nitrogen application will limit aphid populations by reducing succulent growth that is attractive to aphids.Biological - Predators (ladybird beetles, lacewings, syrphid flies and predatory midges) and parasitic wasps are usually capable of providing control of apple aphid on bearing trees and often on young trees. Avoid using pesticides toxic to these beneficial insects once they appear on the trees.
Chemical - Bearing trees - Apply a recommended insecticide if few predators are present, aphid populations are increasing and fruit damage appears imminent. Sprays applied before this level of aphid infestation may destroy beneficial insects and result in the need for additional sprays. Assail applied when codling moth is laying eggs will aid in codling moth control.
Recommended control products:
- Admire (apples)
- Assail (apples, pears)
- Cygon or Lagon (pears, peaches)
- Diazinon (all tree fruits)
- Thiodan or Endosulfan (all tree fruits)
- Malathion (all tree fruits)
NOTE: The sprays listed above will also control other aphids; Admire, Assail and Endosulfan or Thiodan will also control leafhoppers. Research shows that Admire and Assail may increase egg production by pest mites. Therefore do not apply more than two applications of Assail or Admire either alone or alternately per season regardless of target pest (codling moth, aphids, leafhoppers, leafminers) to avoid mite flare-up.
Nonbearing trees - Cygon or Lagon diluted 1:1 with water and applied to the trunk in a band 7-15 cm wide will provide residual systemic control and is least harmful to predators. Apply with a paint brush or hand sprayer. Band treatment provides control equal to sprays but is slower to act.
Apple Grain Aphid (Rhopalosiphum fitchii)
Hosts
Apple, pear, quince, plum, chokecherry, hawthorn, dogwood, grasses.Damage
On rare occasions may cause fruit injury similar to that caused by apple aphid. |
Apple fruitlets distorted by apple grain aphid feeding. |
Identification
Egg - Shiny dark green, oval.Immature - Initially dark green, becoming lighter green, up to 1.8 mm long.
Adult - Light green with a dark green stripe down the back, light coloured legs, 2 mm long.
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Apple Grain aphids. |
Life History
Overwintering eggs on upper twigs and branches hatch when buds open in the spring. There are several generations produced before winged adults appear and move to grasses and grains for the summer. In the fall, adults return to apples and produce a generation that lays overwintering eggs.Monitoring
Inspect trees in the spring to identify the aphid species present.Control
Chemical control is rarely needed. Apple grain aphids attract predators that remain to feed on later-appearing aphid species.
Rosy Apple Aphid
Hosts
Apple, pear, narrow-leaf plantain, dock.Damage
Leaves - Tightly curled on spur growth and at base of shoots; 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.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).
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Jonagold apples damaged by rosy apple aphid |
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Rosy apple aphid damage |
Identification
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.
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Rosy apple aphid colony |
Life History
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.Monitoring
Examine 10 bud or fruit clusters per tree on 10 standard trees per block or 5 clusters per tree on 20 dwarf trees per block, beginning at tight cluster.Control
Chemical - - See 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. Pre-bloom control is most effective in preventing fruit injury. The tight cluster spray of oil plus Diazinon will also control European red mite. Summer sprays will also control other aphids. Endosulfan/Thiodan, Assail and Admire will also control leafhoppers. Recommended control timing and products include:| Timing | Product |
|---|---|
| Tight cluster | Diazinon plus dormant oil |
| Summer | Admire Assail Cygon or Lagon (non-bearing only) Endosulfan or Thiodan Malathion |
Woolly Apple Aphid
Hosts
Apple, pear, hawthorn, mountain ash, cotoneaster.Damage
Twigs and branches - Aphids colonize around wounds on scaffold limbs and on twigs and water sprouts. Colonies can also cause the bark to crack. Perennial canker disease pathogens can infect these wounds.Fruit - Honeydew may drip on the fruit causing russet spots and blackened lenticels.
Roots - Colonies also occur on tree roots and heavy infestations can reduce growth of nursery stock. The root colonies on bearing trees cause re-infestations each year.
Identification
Woolly apple aphids are reddish to brown in colour, up to 2 mm long and covered with a cottony-like white wax. They do not infest leaves. When squashed they leave a red residue.
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Woolly Apple Aphid |
Life History
Adults overwinter on the roots and in protected sites on the tree. In the spring young aphids crawl to new sites. There are several generations per year. Dispersion between trees occurs by wind or birds.Monitoring
Inspect trees in August to see if infestation is general and severe enough to threaten fruit.Control
Cultural - Treat perennial cankers. Remove suckers to eliminate a source of population development as well as prune out water sprouts in August.Biological - Several predators, including syrphid larvae and a parasite, attack woolly apple aphid.
Chemical - See green apple aphid. Field reports indicate Assail and Admire do not provide satisfactory control of woolly apple aphid. Research from Washington State shows diazinon or endosulfan provide satisfactory summer control of woolly apple aphid. When the aphids begin to appear on the trunks of trees in the spring, apply diazinon or endosulfan plus dormant oil to the trunks in sufficient volume to ensure thorough coverage of the trunks and lower limbs.
Green Peach Aphid (Myzus persicae)
Hosts
Peach is the main host; however, apricot, plum, cherry as well as vegetables, field and greenhouse crops and ornamentals are attacked.Damage
Aphid infestations on blossoms and new shoots cause flowers and leaves to curl tightly and shoot to stop growing. Fruitlets may not develop or may drop; young peaches may be deformed and nectarines may be deformed and streaked with russet.
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Green peach aphids
Photo courtesy Agriculture & Agri-Food Canada |
Identification
Eggs oval, shiny blackNymph - Resembles wingless adults but smaller.
Adult - Wingless forms are light green to yellow; winged forms are pale to dark green with a large dusky blotch on the abdomen.
Life History
Overwinter as eggs on host trees, especially peach. Eggs hatch just prior to bloom; nymphs attack blossoms then growing shoots and leaves. After 2-3 generations, winged forms emigrate to summer hosts in June where several generations are produced. In the fall, winged forms return to the spring hosts to lay overwintering eggs.Monitoring
Inspect trees before bloom for aphids on leaves.Control
Biological - Preserve the many predatory insects that feed on aphids by avoiding use of harmful chemicals where possible.Chemical - Field reports indicate green peach aphid is becoming more difficult to control with most currently recommend products. Dormant oil application before bud burst still provides adequate control when applied in sufficient water to ensure thorough coverage.
March 2006
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