Woolly vine or currant scale

Woolly vine or currant scale has a wide range of woody hosts including grape vine, peach, nectarine, currants, gooseberry, pyracantha and mountain ash. Honeydew and sooty mould occur on heavily affected plants.

Woolly vine scale ( Pulvinaria vitis ) with egg masses

Woolly vine scale (Pulvinaria vitis) with egg masses

Quick facts

Common name Woolly vine or currant scale
Scientific name Pulvinaria vitis
Plants affected A wide range including grape vine, peach, nectarine, currants, gooseberry and pyracantha
Main symptoms White egg masses, honeydew and sooty mould
Caused by Sap sucking scale insects 
Timing Spring and summer

What is woolly vine or currant scale?

There are many types of scale insects encountered by gardeners, they are sap sucking true bugs. Like other scale insects the adult woolly vine or currant scale are covered in a waxy ‘scale’ covering.

Adult females of this species mature in September or October, they are 5-7mm long dark brown and convex, immobile and attached to host plants stems. The adult male is winged and pinkish, at only 1.5 mm long it is rarely seen. Males die after mating but the females overwinter and produce white waxy egg masses in May or June. The egg masses are  usually only found on stems and the wax can be pulled out in long threads; these characteristics distinguish this species from other insects that produce white waxy coverings such as cushion scale, fluted scale, horse chestnut scale, woolly aphid and mealybug.

The eggs hatch in June-early July initially the nymphs (crawlers) are mobile before eventually settling down on one year old wood to complete their development.

Symptoms

Heavy infestations of woolly vine or currant scale can leave heavy deposits of sticky honeydew upon which a black non-parasitic fungus sooty mould often grows. Heavy infestations may also result in a lack of vigour in affected plants.

The 5-7mm dark brown insects will be evident upon examination on stems and in spring white waxy egg masses will be evident.

Control

Non-pesticide control

Woolly vine or currant scale is difficult to eradicate. Whilst scraping the insects and egg masses off the stems can help reduce infestations this is unlikely to give good control. It can be worth considering replacing heavily infested plants.

Pesticide control

  • Woolly vine or currant scale is also hard to treat with sprays as the waxy covering gives them some protection and the best results are achieved by spraying against the newly hatched crawlers in early summer. Heavily infested plants may need several applications
  • Scales often remain attached to the plant long after they have died, but new growth will remain free of scales and honeydew if the treatment has been successful
  • Note: There are limitations on the products that can be used on food plants always check that the food plant is listed on the label and follow the manufactures instructions regarding harvest 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 scale insect nymphs. These pesticides have a very short persistence and so may require reapplication to keep scale insects in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults. These organic products can be used on most fruits. 
  • 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). These products can be used on the fruits listed on the label
  • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available, this can be used on some fruits listed on the label
  • Do not spray plants in flower 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)


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