Red scale
Date: 2022 Author: Jianhua Mo
Red scale is the most widespread pest of citrus in New South Wales.
Description
- Females have 4, and males 5, 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 scale cover changes from white in the first stage to reddish-brown in later stages.
- Depending on temperature, red scale has 2 to 5 generations per year in NSW.
Damage
- Red scale infests leaves, fruits, twigs and limbs of all varieties of citrus.
Monitoring
- Check 5 fruits per tree during October–March.
Natural predators
- 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.