Light brown apple moth (a tortricid) is a minor, but sporadic pest of apple in the UK. The life cycle involves at least two generations per annum in the UK.  The moth has a very wide host range and the larvae are known to feed on over 120 plant species.

It is generally controlled by sprays targeted against codling moth and other tortricid pests and in UK horticulture it more often causes damage to cherry and plum because of the limited choice of insecticides available for and used on these crops.

Larvae are leaf-rollers and damage is similar to other leaf-roller species. Damage to foliage is unimportant. Fruit generally suffers from surface damage but young larva may enter fruit through the calyx.

The identification  of larvae is difficult as they are very similar to the larvae of other leaf rollers. The pest should be monitored with pheromone traps weekly from petal fall of apple to the end of August. The economic threshold for treatment is >30 moths per trap per week.

Control  

Several insecticides are approved for control of tortricid moths and/or other caterpillars on apple in the UK and these are also applicable to light brown apple moth. Light brown apple moth is, fortuitously, controlled by several of the sprays targeted against codling moth and fruit tree tortrix moth.

As light brown apple moth is a comparatively new pest to Britain we have only limited experience in controlling it with insecticides and comprehensive efficacy trials have not been done on apple.

• However, experience has shown that indoxacarb (Steward or Explicit) is effective.
• Chlorantraniliprole (Coragen) is also thought to offer incidental control when applied against codling moth.
• Pyriproxyfen (Harpun) may also offer incidental control of light brown apple moth when applied for codling moth control. It inhibits egg hatch, metamorphosis of nymphs to adults and reduces the fecundity of adult females. However, as a new product to the UK in 2020, further experience is required to inform growers and agronomists of its efficacy at controlling light brown apple moth.
• On cherry, Bacillus thuringiensis (Dipel DF) has given disappointing results.
• Spray programmes applied for control of codling and tortrix moths on apple are likely to give good incidental control of light brown apple moth. However, special control measures may be required if damaging populations of the pest develop.
• Sprays should be timed according to sex pheromone trap catches. Larvicides should be applied 7-10 days after a threshold catch of 30 moths per trap is reached, with sprays repeated at fortnightly intervals to give protection through the egg hatch period.
• For details on how to use the various available insecticides, see fruit tree tortrix moth.

 

Insecticides approved for control of codling, tortrix moths (light brown apple moth) or caterpillars on apple

Choice of insecticides – efficacy factors
Active ingredient	Trade name (examples)	Class1	Selectivity	Label rec’s2	Safety to Typhs	Suggested interval between sprays (days)
Bacillus thuringiensis. var kurstaki	Dipel DF	bacterial insecticide	selective to caterpillars	c	safe	7
chlorantraniliprole	Coragen	anthranilic amide	selective	c	safe	14
deltamethrin	Decis Forte etc	pyrethroid	broad spectrum	cm, t	harmful	none stipulated
indoxacarb	Steward, Explicit	oxadiazine	selective	c, cm, ftt, sft, wm	u	Varies with product
pyriproxyfen	Harpun	metamorphosis inhibitor	selective	cm	safe	none stipulated
spinosad	Tracer	neural blocker	selective	C, cm, ftt,sft	safe	u

 

Choice of insecticides – Safety factor Read and follow the label before applying any sprays
	Hazards2				Harvest interval(days)	Max. no. sprays	Buffer zoneWidth (m)
	Anticholin-Esterase?	Humans	Fish &aquatic life	Bees
Bacillus thuringiensis	no	u	u	u	Varies with product	Varies with product	5
chlorantraniliprole	no	h	ed	h	14	2	10
deltamethrin	no	h, i	ed	d	7	u	50
indoxacarb	no	h	ed	u	7	3	15
pyriproxyfen	no	d	t	u	fruit diameter up to 40mm	2	20
spinosad	no	u	ed	h	7	4	40
Keys:     1CSI=chitin synthesis inhibitor, JHA=juvenile hormone analogue2c=caterpillars, ftt=fruit tree tortrix, sft=summer fruit tortrix,  t=tortrix, wm=winter moth 3d=dangerous, ed=extremely dangerous, h=harmful, i=irritant,  t=toxic, u=no hazard specified

 

Control in organic orchards

Light brown apple moth has the potential to cause significant fruit damage in organic orchards.

• If control measures are necessary, sprays of the biological control agent  Bacillus thuringiensis (Dipel DF) should be applied although this has given disappointing results in trials on cherries.
• Spinosad (Tracer) offers a good alternative,  (see ‘Chemical control’ above)
• Also consider cultural control measures.

 

 Further reading