About phylloxera

• Introduction
• Where does phylloxera come from?
• What does phylloxera look like?
• Where is it in Australia?
• How is phylloxera spread?
• What are the symptoms?
• Biology and behaviour of phylloxera

Introduction

South Australia has a reputation for producing world-class wines. The Barossa Valley, Coonawarra, McLaren Vale, Clare Valley, the Riverland and Langhorne Creek are just some of the names that spring to mind when you think of wine and South Australia.

Not only do these regions produce quality wines for the Australian and export markets, they are popular tourist destinations. Who could resist the lure of picturesque vineyards, a Mediterranean climate, sumptuous wines, stunning food and quaint B&Bs?

This lucrative industry must be nurtured and protected to ensure a long and prosperous future.

One risk to the booming South Australian wine industry is a tiny pest called phylloxera (fil-ox-era). This insect attacks grapevine roots, slowly causing a decline in vine health and ultimately destroying the vine. South Australia is currently free of phylloxera. However, as the industry expands and there is more movement of machinery, grapevine material and people between the regions, the risk of spreading phylloxera is increasing. A concerted and diligent approach from everyone involved in the wine industry is required to ensure South Australia remains phylloxera-free.

Where does phylloxera come from?

The phylloxera pest was accidentally transported to most of the world's grapegrowing regions in the mid 1800s through the movement of vine planting material. Phylloxera is a native of North America where it is able to live in harmony with the vines and which have a natural resistance or tolerance to the pest.'

Grapevines grown for winemaking are a different species from the North American vines. They all come from the vitis vinifera species, which originated around the Black Sea and was transported to Europe and then Australia by early explorers.

The Vitis vinifera vines do not have any resistance to phylloxera. The pest gradually destroys the vine's root system, leaving it without any means of taking up the water and nutrients it needs to survive.

All major grape growing regions in the world have been infested with phylloxera, including France, South Africa, California, Italy and New Zealand. These places still manage to grow grapes profitably through the use of resistant rootstocks. Most growers are familiar with the concept of grafting vines onto rootstocks, but many would be unaware that the idea came from having to deal with phylloxera.

What does phylloxera look like?

Phylloxera is a yellow aphid (type of insect), which feeds on vine roots and leaves.The feeding causes galls to form on the developing leaves or roots. The aphids live on the surface of root galls and inside the leaf galls.

Where is it in Australia?

Phylloxera was first detected in Australia in 1877 and was responsible for the near destruction of the Victorian wine industry in the 1880s. Until very recently it was confined to small areas in central Victoria (Nagambie, Upton, Mooroopna) and northeast Victoria (North East, King Valley), in southeast New South Wales (Corowa) and in Camden and Cumberland near Sydney. However, there have been several recent outbreaks in central Victoria (Buckland Valley 2003, Ovens Valley 2003, Murchison 2006 and Yarra Valley 2006).

See map of phylloxera infested zones.

While Australia remains one of the only countries in the world to be largely free of phylloxera, there is no room for complacency. Phylloxera is a major threat to the Australian viticultural industry and growers need to be continually on their guard to prevent a major outbreak.

How is phylloxera spread?

The phylloxera pest can be spread a number of different ways. The most common are via:

• Grapevine materials
• Soil
• Machinery and vehicles
• People
• Grape products such as must and juice

Phylloxera Prevention Protocols have been developed to assist industry reduce the risk of phylloxera.

Studies have shown that vineyards infested with phylloxera can lose 20 per cent of production in only the first year of infestation. Vines generally become uneconomic within 3 to 10 years of infestation.

The spread of phylloxera and the rate of destruction varies depending on factors including soil condition, the age of the vine and how much the vine has been stressed. Good growing conditions can compensate for the damaging effects of phylloxera but replacement with grafted vines will still be eventually required. Infested vineyards on sandy soils are less vulnerable to infestation as phylloxera prefers soils with high clay content that dry and crack, creating pathways for the aphid to reach other vines.

What are the symptoms?

One of the problems with phylloxera is that by the time symptoms of vine decline are noticed, the vines may have been infested for up to two years or even longer.

The above ground symptoms of phylloxera include the yellowing of leaves, reduced yield and a general decline in vine health. Weakening of the vines can take between 1 and 5 years after initial infestation.

Growers can also examine fibrous roots of the vines to check for root galls. The best time to check for these is between November and March and growers are advised to also check vines that appear healthy for phylloxera galls.

There is a better chance of containing phylloxera to a small area and reducing the rate of decline in the vines if diagnosis occurs early.

Biology and behaviour of phylloxera

See the biology and behaviour of phylloxera page.