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Woolly aphid (Eriosoma lanigerum (Hausmann))

Woolly aphid

Woolly aphid colony with wax blown away

Woolly aphid is a sporadic pest of apple, which is sometimes present at low levels in orchards but only increases to cause problems in some years. Damage is expected to occur in years after warm winters when aphid colonies increase in early summer and spread onto extension growth. The entire life cycle is passed on the host tree.

Earwigs, ladybirds and the parasitic wasp Aphelinus mali are important natural enemies of woolly aphid and usually regulate populations to below damaging levels.

Artificial refuges should be provided for earwigs in orchards where woolly aphid is a problem and the use of pesticides harmful to earwigs and other natural enemies should be avoided.

The aphid itself is brown to greyish purple but is easily recognised as it produces conspicuous secretions of white woolly wax.

Orchards should be inspected  for the pest (i.e. for the colonies that produce conspicuous masses of white woolly wax) at the end of blossom, in June and again in mid-summer.

The June assessment is critical. At least 25 trees per orchard should be inspected. If one or more trees in the sample has woolly aphid, in the extension growth, treatment with an insecticide is justified.

Control  

  • Flonicamid (Mainman) is specifically recommended for control of woolly aphid on apple.
  • Pirimicarb (Aphox etc.) can also give good control if applied in higher spray volumes in warmer weather conditions.
  • Flonicamid (Mainman, Teppeki) or pirimicarb (Aphox etc) are good choices because they are selective, have low toxicity to natural enemies and are partially systemic.
  • Use of synthetic pyrethroids, which are harmful to natural enemies, should be avoided.
  • Thiacloprid (Calypso) has little or no effect on woolly aphid. Calypso may possibly be harmful to earwigs, the most important natural enemy of woolly aphid. If this is the case, sprays of thiacloprid (Calypso) in mid- and late summer when earwigs are present in the tree, could cause later outbreaks of woolly aphid.
  • Higher volume sprays are likely to give best results.

 

Insecticides approved for use on apple which are recommended to control woolly aphid or offer some incidental control when applied to control other pests

Thiacloprid (Calypso) is not listed here because although it is effective against other aphid species on apple and many other pests, it is ineffective against woolly aphid

Choice of insecticides – efficacy factors

Active ingredient Trade name (examples) Class Selectivity Approved for control of Safety to Typhs 
acetamiprid Gazelle neonicotinoid broad-spectrum, systemic Aphids safe
cypermethrin various pyrethroid broad spectrum Aphids, apple sucker, capsids, caterpillars, codling & tortrix moths, sawfly harmful
deltamethrin Decis etc. pyrethroid broad spectrum Aphids, apple sucker, capsids, codling & tortrix moths, sawfly harmful
dodecylphenol ethoxylate Agri 50E physical acting insecticide broad spectrum Aphids, leafhoppers, mealy bugs, spider mites harmful
fatty acids Savona soap broadspectrum Aphids, leafhoppers, scale insects harmful
flonicamid Teppeki, Mainman neonicotinoid selective Aphids and woolly aphid safe
maltodextrin Majestik polysaccharide broad spectrum Aphids, spider mites harmful
pirimicarb Aphox etc. carbamate selective aphicide, trans-laminar Aphids safe
pyrethrins Spruzit extract from pyrethrum broad spectrum Aphids, apple blossom weevil, caterpiallars, spider mites harmful

Choice of insecticides – Safety factors

  Hazards Harvest interval(days)

 

Max. no. sprays Buffer zoneWidth (m)
Anticholin-esterase?  Humans Fish & aquatic life Bees
acetamiprid no u h u 14 2 20
cypermethrin no h, i ed d 0 4 18
deltamethrin no h, i ed d 7 u 50
dodecylphenol ethoxylate no u u u 0 u u
fatty acids no u h u 0 u sm
flonicamid no u h u 21 3 sm
maltodextrin no i d d 0 20 sm
pirimicarb yes t, c h 3 u sm
pyrethrins no h,i ed d 0 4 50
h=harmful, i=irritant, d=dangerous, ed=extremely dangerous, t=toxic, c=closed cab required for air assisted sprayers, sm=statutory minimum of 5 m for broadcast airassisted sprayers u=uncategorised/unclassified/unspecified* approval for use and storage of all products containing nicotine is allowed only until 08 June 2010

 

Control in organic orchards

In organic orchards where the pest is often troublesome, emphasis should be placed on cultural control measures such as the provision of artificial refuges for earwigs and, if practicable, physical destruction of colonies in spring.

  • High volume sprays of fatty acids (Savona) should be applied when damaging infestations develop.

 

 Further reading