Pests & Diseases

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Light Brown Apple Moth

Epiphyas postvittana 

Affected

Pome fruit and apricots, though other stone fruit can be infested. 

Description

Young larvae of the light brown apple moth (LBAM) are pale yellow and small (about 1 mm long) and settle on the underside of leaves where they spin a protective web in which they feed. After their first moult they abandon the web to construct a nest by webbing together leaves and or fruit. LBAM always feed under shelter. They continue to feed from this nest until mature at which stage they are up to 25 mm long, pale to medium green in colour with a darker green central stripe and a brown head.
The moths which are buff-coloured and about 10 mm long are seldom seen.

When and where to look

Larvae of light brown apple moth are present for most of the year, either in the trees or on weed hosts. At flowering, check amongst the blossom clusters for webbing and presence of the larvae. From then on until harvest leaves should be inspected for the webbed nests constructed by the larvae. Damage is most common in the lower half and central parts of the tree. 

Damage

LBAM feeds from within the sheltering nest it constructs. Damage to leaves is not of commercial importance in mature trees. However LBAM also feeds on fruit which often form part of the shelter. Damage is usually confined to the surface of the fruit, where tracks are eaten away. Sometimes the larvae will burrow into the fruit, particularly around the stem.
Fruit damage to stone fruit normally occurs in the 2 weeks leading up to harvest, but LBAM will damage pear fruit from fruit set on. 

Control

Natural enemies of the egg, larvae and pupa can maintain adequate control of this pest if the predators have not been killed by orchard sprays for other pests. Trees should be monitored on a regular basis for presence of the pest.
LBAM damage of fruit is most severe where clusters of fruit provide shelter for it. Removal of these fruit clusters at thinning will reduce the amount of damage sustained to fruit.
On stone fruit Bacillus thuringiensis sprays can be applied for the biological control of LBAM. Timing is important as this agent is only effective on young larvae. Good spray coverage is essential as the larvae live in sheltered locations and it is necessary for the sprayed leaf to be eaten by the larvae to effect control. Repeated spraying (every 10 - 14 days) is necessary for good control where heavy infestations exist. If the number of larvae in the orchard is unacceptable 3 - 4 weeks prior to harvest a registered insecticide can be used to control larvae prior to when the majority of fruit damage occurs.