Apple Sucker

Key Points

  • Apple sucker infestations rarely cause significant crop losses in well-managed orchards
  • The presence of honeydew and white, waxy threads are characteristic of attack
  • Lorsban WG should be applied at green cluster timing
  • Applications of Lorsban WG can control Apple sucker and many other fruit pests

Introduction

Apple sucker (Psylla mali) infestations used to be common in apple orchards, causing serious damage where they occurred. In recent times the adoption of integrated control programs, incorporating the use of effective insecticide treatments, means serious infestations are rarely encountered in well-managed orchards.

Large populations of Apple sucker nymphs can cause browning of petals and even death of heavily attacked blossom buds. This occurs in the spring and is a result of nymphs sucking sap from the blossom trusses. The damage is often mistaken for frost damage due to the similarity of symptoms.

Biology

Apple suckers only colonise apple trees and their life cycle is based on one generation each year. Overwintering occurs as barely visible, oval, straw-coloured eggs laid along leaf scars on the fruit spurs. Eggs are occasionally laid at the base of leaf buds or scattered along the twigs.

Egg hatch normally starts from April onwards, at the bud burst stage, and is complete by the green cluster stage. Newly-hatched nymphs have distinctive red eyes and an orange-brown, flattened body. Honeydew deposits and white waxy threads are easily found on infested trusses. After the second moult nymphs become bright green in colour and rudimentary wings are apparent.

The first adult Apple suckers appear approximately 4 – 6 weeks after hatching. At first, the bodies are greenish-yellow, but become much darker later. Adults grow to 3mm and have transparent wings with green veins. Adult feeding occurs throughout summer and in to early autumn with eggs being laid from the end of August. Once eggs have been laid the adult Apple suckers die.

Product Choice

Applications of Lorsban* WG (active ingredient chlorpyrifos) at the green cluster stage, i.e. the timing used for control of aphids and caterpillars, will control infestations of Apple sucker. Do not apply to crops in flower or to those in which bees are actively foraging. Do not make applications when flowering weeds are present.