Red scale

Date: 22 Aug 2002   Author: Jianhua Mo

Red scale close up

Red scale is the most widespread pest of citrus in New South Wales.

Description

  • Females have four, and males five, development stages.
  • All stages are sessile (non-free-moving) except the early part of the first stage (crawlers) and adult males (winged).
  • The scale cover of the female is circular (about 2 mm diameter), whereas that of the male is elongated.
  • The colour of the scale cover changes from white in the first stage to reddish brown in later stages.
  • Depending on temperature, red scale has two to five generations per year in NSW.

Damage

  • It infests leaves, fruits, twigs and limbs of all varieties of citrus.

Monitoring

  • Check five fruits per tree during October–March.

Natural enemies

  • Aphytis wasp
  • Ladybirds
  • Chilocorus
  • Predatory mites

Control measures

  • Take appropriate actions if 10% or more of fruits of early varieties are infested, or 15–20% or more of later varieties are infested. Appropriate actions include releasing parasitic wasps and the application of petroleum spray oil.
  • When choosing the latter option, time the spray when young scales are predominant.

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