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Ministry of Agriculture, Food and Rural Affairs

Rosy Apple Aphid (RAA)

Rosy apple aphid nymph Rosy apple aphids Rosy apple aphids damage to terminal Pigmy fruit from feeding damage
Click to enlarge.

Beginner

Scientific Name
Dysaphis plantaginea

Identification
Eggs:

  • 0.4 mm in length,
  • Oval shaped,
  • Bright yellow when first laid, gradually change to greenish-yellow and eventually black.

Nymphs:

  • Passes through five instars, increasing in size from 0.4-2.0 mm,
  • Young nymphs are pale yellow or pink, and become rosy brown or purple as they grow and feed,
  • Have long cornicles (tail pipes) at the base of the abdomen,
  • Have long antennae extending almost half the length of the body.

Adults:

  • Similar to nymphs in appearance,
  • May be winged or wingless,
  • 3 mm in length,
  • Dark purple-pink and found in colonies on extension and terminal growth.

Damage:

  • Damage occurs when saliva translocates to the leaves or fruit.
  • Affected leaves appear tightly curled and puckered, while fruit remain small, deformed (pigmy fruit) and unmarketable,
  • RAA are rarely found attacking young and actively growing shoots.  They generally are found feeding on foliage, flower stalks and young fruits,
  • Aphids produce honeydew that drips onto leaves and fruit,
  • Sooty fungus colonizes the honeydew, discolouring the fruit,

Often Confused With

  • Green apple aphid- Immature green apple aphids differ in colour from rosy apple aphids and have shorter antennae and less developed cornicles than immature rosy apple aphids. Green apple aphids are usually found in colonies on young terminals of apple trees, while rosy apple aphids are found on fruit clusters.

Period of Activity
The rosy apple aphid is considered a pest in apple orchards at the end of tight cluster until the beginning of middle summer. In the past it is rarely a pest in orchards after petal fall, but in recent years infestations have occurred in orchards later in the summer.

Scouting Notes
Check for rosy apple aphids every week, beginning at tight cluster and continue until late June. Cortland, Ida Red and Golden Delicious are all susceptible cultivars to monitor for rosy apple aphid. For every 10-15 ha, examine 5 clusters from each of 20 trees for dwarf and semi dwarf plantings. For larger trees, examine 10 fruit clusters from each of 10 trees. A cluster is considered infested if more than 20 aphids are present. Check the interior portion of the tree – where rosy apple aphids usually appear first.

Thresholds
Chemical control is recommended if more than 5% of fruit clusters are infested and few predators are identified. Monitor for aphid predators around rosy apple aphid colonies. Beneficial insects may make chemical control unnecessary.

Advanced

Scientific Name
Dysaphis plantaginea

Identification
Overwintering eggs on bark and twig surfaces are 0.4 mm in length and oval shaped. When first laid, eggs are bright yellow, gradually change to greenish-yellow and eventually black.

The nymph passes through five instars, increasing in size from 0.4-2.0 mm. Young nymphs are pale yellow or pink, and become rosy brown or purple as they grow and feed. Nymphs have long cornicles (tail pipes) at the base of the abdomen and long antennae extending almost half the length of the body.

Adults are winged or wingless and 3 mm in length. In early spring, rosy apple aphids move to developing fruit clusters and become reproductive adults during bloom, taking two to three weeks to mature. Hatched nymphs are wingless females called stem mothers when they mature. Adults are a dark purple-pink and found in colonies on extension and terminal growth.

Young aphids hatch in spring, damaging the outside of fruit and leaf buds by sucking sap from tissues. During feeding, aphids inject a toxin that deforms leaves and fruit. Aphid feeding tightly curls and puckers leaves, hiding the aphid colony. Rosy apple aphids produce honeydew that drips onto leaves and fruit. Sooty fungus colonizes the honeydew, discolouring the fruit. Often ant feeding on honeydew is associated with aphid colonies. The most serious rosy apple aphid damage occurs when saliva translocates from the leaves to fruit, causing apples to remain small, deformed (pigmy fruit) and unmarketable. Toxic saliva reduces growth of roots and other woody tissue. Toxins in aphid saliva serve as a “stop drop”, preventing the fruit’s abscission (natural separation from the tree) at normal harvest. Rosy apple aphid is rarely found attacking young and rapidly growing shoots, restricting itself to foliage, flower stalks and young fruits.

Often Confused With

  • Green apple aphid- Immature green apple aphids differ in colour from rosy apple aphids and have shorter antennae and less developed cornicles than immature rosy apple aphids. Green apple aphids are usually found in colonies on young terminals of apple trees, while rosy apple aphids are found on fruit clusters.

Biology
Females deposit eggs on bark – especially at the base of the buds – in the fall. Eggs begin to hatch as tree buds open in the spring and continue hatching over a two-week period. Nymphs feed on the outside of leaf and fruit buds until leaves unfold, then work their way down inside clusters and begin sucking sap from stems and newly-formed fruits. A single nymph feeding for 24 hours can cause the leaf to be curled when it unfolds.

Mature females produce live young shortly after or during bloom. The second generation matures and produces live young two to three weeks after petal fall. Populations are usually greatest in the inner and upper parts of the canopy. The second generation requires 4-40 days to reach maturity and produce young. Unmated females produce live young (parthogenesis) and only females are produced during the summer. Most second generation rosy apple aphids are wingless females. Each female produces 120-185 offspring.

There are generally three generations of rosy apple aphid produced on apple, with the second generation occurring two to three weeks after petal fall and the third generation appearing by mid to late June. By early to mid July, most aphids have developed wings and dispersed to summer hosts such as narrow-leaf and broadleaf plantain or dock. In some seasons, wingless females of the third generation produce a fourth generation on apple.

Several more generations develop on summer hosts until fall, when winged females return to apple trees and produce live female young. These females develop on apple, mate with males, and deposit eggs that overwinter the following spring.

Period of Activity
The rosy apple aphid is considered a pest in apple orchards at the end of tight cluster until the beginning of middle summer. In the past it is rarely a pest in orchards after petal fall, but in recent years infestations have occurred in orchards later in the summer.

Scouting Notes
Check for rosy apple aphids every week, beginning at tight cluster and continue until late June. Cortland, Ida Red and Golden Delicious are all susceptible cultivars to monitor for rosy apple aphid. For every 10-15 ha, examine 5 clusters from each of 20 trees for dwarf and semi dwarf plantings. For larger trees, examine 10 fruit clusters from each of 10 trees. A cluster is considered infested if more than 20 aphids are present. Check the interior portion of the tree – where rosy apple aphids usually appear first.

Thresholds
Chemical control is recommended if more than 5% of fruit clusters are infested and few predators are identified. Monitor for aphid predators around rosy apple aphid colonies. Beneficial insects may make chemical control unnecessary.

Management Notes

  • Aphids have many natural enemies including hover fly larvae (Syrphidae), lacewing larvae (Chrysoperlidae and Hemerobiidae), lady beetle larvae/adults (Coccinellidae), mullein bug (Miridae), minute pirate bug (Anthocoridae), earwigs and some parasitic wasps (Braconidae).
  • The natural enemy complex can be disrupted by insecticides applied against other pests. When possible, use pesticides less likely to disrupt predator populations. For more information on the toxicity of pesticides to beneficial insects click here.
  • Unpruned trees provide favorable conditions for aphids and greatly limit effectiveness of control.
  • A cool, wet spring also favours aphid development by providing conditions unfavorable for aphid parasites and predators.
  • Aphids are killed by extreme temperatures (low temperature or sudden changes during the winter or hatching period), moisture (cold rains at or just before hatching time can kill young aphids),
  •  If chemical control is justified, apply insecticide in high volumes of water for good coverage.
  •  If possible, spray only susceptible cultivars where the threshold has been reached.
  • Detect rosy apple aphid infestations early, before mid June.  Avoid late season applications when chemical has little chance of contacting aphid colonies once leaves are curled. 
  • Systemic pesticides are required to control rosy apple aphid once leaf curling has occurred.
  • Dormant oil sprays to control European fruit scale or San Jose scale can suppress rosy apple aphid by killing overwintering eggs. See OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :