Mealy cabbage aphid

Mealy cabbage aphid is common on brassicas. Its presence on established plants can usually be tolerated however, the aphid can make kale inedible and the growth points of young brassica can be severely affected.

Mealy cabbage aphid

Mealy cabbage aphid

Quick facts

Common name Mealy cabbage aphid
Latin name Brevicoryne brassicae
Plants affected Cabbage, cauliflower, Brussels sprout, swede and other brassicas
Main symptoms Greyish white aphids cluster underneath the leaves and on growing points. Leaves distorted and discoloured on young plants
Caused by A sap-sucking insect
Timing April-October

What is mealy cabbage aphid?

Mealy cabbage aphid is a greenfly with distinct whitish or 'mealy' appearance. They are sap-sucking insects that feed on cabbages and other brassicas.

Symptoms

On first appearances this insect may be confused with cabbage whitefly. However, mealy cabbage aphid does not fly up in a white cloud when disturbed. Other symptoms to look out for include:

  • Dense colonies of greyish-white aphids, up to 2.5 mm long, clustered on the underside of leaves and on the growing points
  • The leaves develop a whitish-yellow discolouration where the aphids are feeding
  • On young plants, the foliage develops in a distorted manner and the growing point may be killed
  • In addition to edible and ornamental brassicas, this aphid can also be found on some related wild plants, such as charlock and shepherd’s purse

Control

Look for aphids on foliage, especially on more vulnerable young plants in late spring to early summer.

Non-pesticide control

  • Where possible tolerate infestations of mealy cabbage aphid
  • Naturally occurring aphid predators can reduce populations of this aphid
  • Dispose of old brassica plants once they have finished cropping to reduce the risk of the next season’s plants becoming infested
  • Manually squashing aphids can reduce infestations but is unlikely to eliminate this insect

Pesticide control

  • On food plants ensure that the crop is listed on the pesticide label and that all instructions are followed, particularly those on harvest interval, spray interval and maximum number of applications
  • Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of aphids. These pesticides have a very short persistence and so may require reapplication to keep aphid numbers in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults
  • More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer) and cypermethrin (e.g. Py Bug Killer)
  • Two (in some cases three) applications of cypermethrin, deltamethrin or lambda-cyhalothrin can be used per crop and there is a 7 or 14 day harvest interval. The organic pesticides are usually not restricted in number of applications and could be used up to one day before eating the produce. Always check the label
  • Plants in flower should not be sprayed due to the danger to pollinating insects
  • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

Mealy cabbage aphid overwinters on its host plants as eggs that are laid on stems in late autumn, although in mild winters infestations of active aphids may persist through the winter.

For most of spring and summer, the aphids are present as wingless females that give birth to live young.

Winged forms develop when plants become heavily infested, allowing the aphids to migrate to new host plants.


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