Pyriform scale

Alert

Have you seen Pyriform scale? It was detected in Western Australia in 2015 and is absent from Queensland.

Be on the lookout and report it.

Under Queensland legislation, if you suspect the presence of this disease in any species of animal, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

Early detection and reporting are key elements in controlling this pest.

Movement restrictions are in place to prevent pyriform scale from being introduced into Queensland.

Pyriform scale is a sap-sucking scale insect that poses a threat to a range of Australian horticulture industries.

This pest can feed on many horticultural, ornamental and native plants.

It produces large amounts of honeydew on which sooty mould can grow.

Pyriform scale infestation results in poor plant growth, leaf drop and a reduction in fruit size and quality.

Cause

Pyriform scale (Protopulvinaria pyriformis) is a soft scale insect.

Other names

  • Heart-shaped scale

Description

Adult

  • Raised, scab-like on the underside of leaves.
  • Pear-shaped (or heart-shaped).
  • Yellowish-brown to darker brown with a characteristic white fringe.
  • 2–4mm long.

Nymphs

  • Similar to adults in shape, but more flattened.
  • Initially translucent green, changing to light green with age.
  • Early-stage nymphs are commonly called 'crawlers' because they have legs and are able to move short distances within or between trees.

Egg

  • Carried beneath the adult female's body.

Plant stage and plant parts affected

  • All plant stages from seedling to mature plants are affected.
  • Predominantly affects leaves and fruit.

Plant damage

  • Direct feeding on plant sap which affects the ability of the plant to take up nutrients.
  • Poor plant growth.
  • Leaf drop.
  • Reduction in fruit size and quality.
  • Indirect damage is caused by the growth of sooty mould on the honeydew secreted by the scales.
  • Sooty mould covers leaves and fruit, reduces the amount of sunlight available to the plant for growth.

May be confused with

Other scale insects with a similar shape may be confused with pyriform scale.

Pyriform scale requires expert identification. Report pear-shaped/heart-shaped scale insects to 13 25 23.

Distribution

Pyriform scale has a widespread distribution that includes Africa, South, Central and North America, Europe and the Middle East.

Pyriform scale has been detected in Western Australia. The pest has not been found in Queensland.

Hosts

Pyriform scale can infest a broad range of horticultural, ornamental and native host plants from over 34 plant families including:

  • avocado
  • banana
  • bauhinia
  • camellia
  • canna
  • citrus
  • coffee
  • eucalyptus
  • fig
  • frangipani
  • gardenia
  • guava
  • hibiscus
  • ivy
  • laurel
  • lilly pilly
  • mango
  • myrtle
  • orchids
  • passionfruit
  • papaya
  • pomegranate

Life cycle

  • The entire lifecycle usually takes place on the lower leaf surface.
  • Females are able to reproduce without males (asexual reproduction).
  • Each female can lay up to 300 eggs, which she carries under her body.
  • Nymphs hatch from the eggs and settle on lower leaf surfaces to feed.
  • Nymphs go through 3 growth stages (instars) before reaching adulthood.
  • Crawling nymphs and female adults are capable of movement.

Impacts

Pyriform scale can infest a broad range of plants, causing poor growth, and reducing production and yield. This pest poses a threat to Australia's avocado, citrus, mango, banana, passionfruit, forestry and nursery/garden industries, as well as to our urban and natural environments.

How it is spread

Moving infested host plant material, such as pot plants, can spread this pest.

Localised spread can also occur within and between plants and trees as the nymphs and adults are able to crawl and may also be blown in the wind.

Monitoring and action

Check for the presence of pyriform scale on plants:

  • that are stunted and unthrifty
  • with excess honeydew and/or sooty mould
  • with excessive ants
  • with excessive leaf or fruit drop.

Look for pear-shaped, raised scab-like scale insects, up to 4mm long, on lower leaf surfaces.

Report suspect pyriform scale to Biosecurity Queensland on 13 25 23.

Prevention

Legal requirements

Pyriform scale is prohibited matter under the Biosecurity Act 2014.

Report suspected pyriform scale to Biosecurity Queensland immediately on 13 25 23 or contact the Exotic Plant Pest Hotline on 1800 084 881.

If you think you have found pyriform scale, you must take all reasonable and practical steps under your control to minimise any associated risks. This is called a general biosecurity obligation (GBO).

Movement restrictions are in place to prevent the introduction of pyriform scale to Queensland.

You need a biosecurity certificate to bring host plants into Queensland from Western Australia.

The Queensland Biosecurity Manual (PDF, 1.4MB) outlines the potted plant varieties affected and the risk minimisation measures that must be taken.

Further information