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Grape phylloxera

Leaf galls on Cv. Seyval Blanc. 12KB

Leaf galls on cv. Seyval Blanc.
What is it ?

Grape phylloxera, Daktulosphaira vitifoliae (synonym: Viteus vitifoliae) is a destructive pest of grapevine. It was introduced into Europe from North America in the 1860s, resulting in the devastation of over 2 million hectares of vines in France, known as the "great wine blight". It has spread to most vine growing areas of the world and is locally established in the UK, but is under containment.

The small, aphid-like insect feeds by piercing the plant tissue and sucking the sap, causing the plant to produce characteristic swellings or galls in response to its feeding. There are distinct foliar and root feeding forms. The European vine (Vitis vinifera) is particularly susceptible to root galling, which can result in the death of the plant. However, the roots of American species of Vitis are more resistant to phylloxera and control of the pest has been achieved in most countries by grafting vines onto resistant or tolerant American rootstocks.
What damage does it cause?
The expression of symptoms depends upon the type of vines being grown and also upon climatic conditions. Leaf galling does not appear on all varieties of vine and, as root galling is difficult to detect, an infestation may go unnoticed until it is widely established on a vineyard.
Root Galls
  • Root-feeding stages are the most damaging, causing a loss in plant vigour, wilting and leaf yellowing. Vines may eventually die within 3-10 years.

  • Galls are most damaging on the mature roots, interrupting the vascular system of the plant and causing root deterioration and rotting, assisted by secondary bacterial and fungal infection.

  • Root stages of phylloxera can crawl through cracks in the soil surface to infest adjacent plant roots and they can also be spread by soil on boots or machinery.
Root galls on grapevine 10KB

Root galls on grapevine
  • Damage is most severe on European vines growing from their own roots.

  • Tolerant rootstocks will support populations of phylloxera which produce some root galling, but the root galls do not have a detrimental impact on the plant or significantly reduce grape yields.
Leaf galls
  • Leaf galls mainly occur on the underside of leaves. They are initially green but become increasingly red and pronounced as they develop. They can be distinguished from the mite galls of Colomerus vitis which are green blisterlike swellings on the upper leaf surface with felty patches on the underside.

  • Phylloxera leaf galls are most commonly found on American hybrid vines, such as Seyval Blanc, (a popular variety in the UK) and provide a useful indicator of potential root infestation.

  • Leaf galls do not usually cause economic damage since the prolific foliar growth of vines compensates for any premature leaf drop. However, foliar stages do aid further increase in the population of phylloxera and can lead to dispersal to other vines, particularly during leaf-trimming and harvesting using machinery or by hand.
What is the life cycle?

The life cycle is complex with distinct root and foliar cycles, although in some cases the foliar cycle does not occur.

Root feeding stages can overwinter in the soil and continue an asexual cycle without leaf stages occurring. Leaf galls may be present one year but absent the next, depending on climatic conditions. The pest population multiplies rapidly throughout the growing season, with a potential rate of population increase similar to that of aphids.

The production of foliar stages depends on the species of vine and climatic conditions.

  • If favourable conditions prevail, winged females may be produced in late summer. These migrate from the roots to the aerial parts of the plant where they deposit both male and female eggs. These sexual forms mate, after which the females deposit winter eggs on the bark of the vine.

  • In the spring, asexual nymphs emerge and migrate to the upper leaves to feed. This feeding induces gall formation by the plant. The asexual nymphs mature into females which each can lay several hundred eggs. These in turn hatch to form more females to continue several asexual generations during the summer, building up high populations.

  • In late summer many of the nymphs migrate to the roots to begin or continue the root cycle.
What should I do?
  • Phylloxera can be introduced onto vines either as eggs on the stems or on infested roots. Ensure that newly imported vines are certified as free from phylloxera. A number of quarantine treatments are available for dormant vines, such as fumigation and hot water dipping.

  • Only grow varieties grafted onto tolerant rootstocks, e.g. American and American hybrids. The use of tolerant varieties is the only effective means of control of this pest.

  • Varieties such as Seyval Blanc are highly susceptible to foliar stages of the pest. Planting of this variety is not recommended, particularly in areas known to be at risk of phylloxera.
This is a notifiable pest. If you see or suspect the presence of phylloxera you must immediately inform your local Defra Plant Health and Seeds Inspector or the PHSI HQ, York (Tel: 01904 455174, Fax: 01904 455197 Email:planthealth.info@defra.gsi.gov.uk )

Department for Environment, Food and Rural Affairs
1997 PB3044(c)
CENTRAL SCIENCE LABORATORY
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Page last modified: 20 Nov 2006
Page published: 27 May 2004

Department for Environment, Food and Rural Affairs