What is Phylloxera?
The Grape phylloxera (Daktulsphaira vitifoliae) is an insect which is native to eastern North America. In America there is a winged form of phylloxera, but this form has been rarely observed in Australia and appears to be sterile.
Adult phylloxera are 1mm long and yellow in colour in summer, tending to brown in winter (see figure 1). They feed exclusively on grapevines and may be found in the vineyard throughout the year, with peak populations in January and February.
Eggs (figure 2), which have hatched during spring into nymphs, develop as crawlers (figure 3) through several stages and may be found in the canopy.
Following several crawler stages from 5 to 8 weeks to adulthood, they lay eggs of up to 200 eggs per cycle, and are capable of between five to nine overlapping cycles per season. This depends on the nutrition and environmental conditions available as well as the virulence of the phylloxera strain. Small numbers survive over winter by sheltering underground on vine roots and occasionally under the bark at the base of the vine.
Below are examples of wingless adults (figure 4) and winged adults (figure 5).
As phylloxera feed by puncturing the root surface, the vine responds by forming galls on root hairs and swellings on older roots (see figure 6). On the root hairs, these galls have a characteristic hook-shaped form and this damage stops the growth of the feeder roots. On larger roots, there can be swelling of the root tissue and subsequent decay through secondary fungal and bacterial infections. This, and the loss of feeder roots, causes Vitis vinifera to die. American Vitis spp (rootstocks) also react to phylloxera feeding but not to the same extent as they have evolved to tolerate phylloxera.
Life cycle of phylloxera in Australia
History of phylloxera in Australia
The initial impact of phylloxera was first experienced in France in the 19th century, following the substantial movement of botanic collections of North American plants into Europe. These plants were hosts for pests and diseases that affected European plants, with the first impact on vines made by powdery mildew in 1847, followed by another wave of disease causing vine collapse from 1864. With the cause unknown, phylloxera spread rapidly, as the exchange of propagation material between regions was common practice. Phylloxera was finally identified in 1872, but not before substantial areas of vines were destroyed.
Recognising that American Vitis spp were resistant to powdery mildew, French viticulturists allowed importation of material from the north-eastern United States until the 1860s. In 1878 the ‘Agreement of Berne’ set international rules on outbreak notification and border restrictions on movement of propagation material.
The first detection of Phylloxera in Australia was near Geelong in 1877. Once several vineyards were found to be infested, a policy of destroying vineyards and leaving them fallow for many years to eradicate the insect was implemented based on the French experience. Unfortunately, this early attempt at eradication was unsuccessful and phylloxera was later detected in other parts of Central and North East Victoria.The first detection in New South Wales was in 1884 at Camden and further infestations were subsequently found nearby. Phylloxera was first found in Queensland at Enoggera, Brisbane, in 1910 and has not been detected in that state since the 1960s.
South Australia, which had not received infected material, banned movement of vine material under the powers of the Vine Protection Act of 1874. The first Phylloxera Act was enacted in 1899. Then in 1995, the Act become Phylloxera and Grape Industry Act 1995 with government support for levies in order to undertake its duties under the Act.
Through quarantine measures, implementation of farm-gate hygiene practices and continued vigilance, the grapegrowing states of South Australia, Western Australia and Tasmania have not become infested with phylloxera; alongside large parts of Victoria and New South Wales. Queensland is thought to be free of Phylloxera.
This strict ban on all importation of grape material to South Australia was in place until 1964. Since then, amendments to the importation of grape material and machinery have been adjusted as science has offered more information regarding the management of this pest. See Phylloxera Regulations for more information on the importation of grape material.
The first signs of a phylloxera infestation include –
- Slow and stunted shoot growth, and
- Early yellowing of leaves as they lose functionality initially. leaf yellowing will normally be seen in two to three neighbouring vines – usually, but not always within the same vine row.
Symptoms may appear within 3 years under certain conditions, with vine death within 5-6 years depending on the phylloxera strain.
In the mid stages of infestation, an infested vineyard area looks like an ‘oil spot’ in its spreading pattern as the phylloxera move from vine to adjacent vine and from row to row, spreading out from the roots of the vine where it was first introduced. Soils such as cracking clays facilitate the spread in contrast to sandy soils that are more difficult for crawlers to move through. Wet seasons and well irrigated vineyards help the vine to fight off the damage cause by phylloxera.
Phylloxera can only survive for up to 8 days in warm weather without feeding on grapevines and considerably longer in cool conditions. Further, phylloxera is a soft bodied insect with poor tolerance for heat and a preference for high humidity. Phylloxera infestations have the capability of moving naturally up to 100-200m per season in a vineyard.
How is phylloxera spread?
Analysis of the phylloxera outbreaks in Europe in the late 19th century indicates that movement of infested plant material was the cause of the widespread infestations.
Additional causes of Phylloxera contamination, can be spread by –
- Grapevine materials – rootlings, cuttings, potted vines, leaves, shoots
- Soil from a vineyard
- Movement of machinery, equipment and vehicles
- Whole grapes
- Grape products such as must and juice
- People and clothing
The natural spread of Phylloxera within a vineyard is approximately 100-200m per year.
Inspecting vineyards for phylloxera
Growers are strongly encouraged to monitor their vines regularly to look for signs of vine damage which may be attributable to a P\phylloxera infestation. The best time to check for these is between January and February.
Farm-gate hygiene practices by grapegrowers and vineyard staff can play a vital role in protecting South Australia from phylloxera, by inspecting their vineyards for signs of its presence on a regular basis and reporting any suspicions straight away. This can be done while you, your staff or contractors are in the vineyard – spraying, checking irrigations, yield forecasting or pest and disease monitoring.
For more detailed information, the Board has developed –
- Checklists for growers, vineyard managers, contractors and cellar door sales managers – about how to protect their vineyard, and
- A brochure on A grapegrowers guide to inspecting vineyards for phylloxera.pdf
|What is phylloxera?||Phylloxera is a tiny yellow insect that destroys grapevines by killing their roots.|
|Why is it so bad for vineyards?||It can kill vines and can’t be removed from vineyards once established. The only way to remove phylloxera is to remove all vines.|
|Where does phylloxera originate?||Phylloxera is native to eastern and southern USA, where it lives on native American vines.|
|Where is phylloxera present in the world?||Phylloxera is in every wine producing country in the world except Chile. In Australia, phylloxera is only found in small areas of central, eastern and north eastern Victoria and the south east of New South Wales.|
|How is phylloxera spread?||Phylloxera is spread by vine planting material, soil, machinery, people, vehicles, grapes and moving from infested to non-infested vineyards.|
|How do phylloxera insects reproduce?||The adults are all female and are able to reproduce asexually. One adult female is capable of laying 200 of more eggs per cycle and can have several breeding cycles in its lifetime. This means only one insect is needed to infest a vineyard.|
|How does phylloxera kill vines?||The phylloxera insect lives and feeds on the roots of grapevines, gradually injuring the root system. Secondary fungal infections then occur as the roots are injured. As the roots die, so does the vine.|
|Is there a cure for phylloxera?||There are currently no effective chemical treatments, no biological controls and it is possible to eradicate phylloxera by the removal of all vines. The only effective measure for managing phylloxera is to replant on resistant rootstocks.|
|When is the best time to look for phylloxera?||The best time is between December and January when phylloxera is actively breeding.|
|If phylloxera is ever found in South Australia what will happen?||Vinehealth Australia and Primary Industries and Resources SA (PIRSA) have developed a plan for managing an outbreak. Initially vineyards within a 5km radius of the infestation site would be quarantined. Further zones would be established depending on the contiguous nature of vineyards.|
|What are phylloxera resistant rootstocks?||Phylloxera resistant rootstocks are from Native American vines, which have evolved with phylloxera. Phylloxera still lives on rootstock varieties, however, does not cause any decline in vigour or yield.|
|What can a grower do to prevent phylloxera?||The best way for a grower to prevent phylloxera is to adopt best practice protocols.|
Corrie A et al. (2001) “Life cycle of grape Phylloxera in Australian vineyards: management implications”, The Australian Grapegrower and Winemaker, July 13-16.
Dunstone R, Corrie A amd Powell K ; (1998) “Preventing the spread of Phylloxera”. The Australian Grapegrower and Winemaker ,420 14-16.
Herbert K , Hoffmann A, Powell K, (2008) “Assaying the potential benefits of thiamethoxam and imidacloprid for Phylloxera suppression and improvements to grapevine vigour”.
Herbert K, Powell K, McKay A, Hartley D, Herdiona, Opeel-Keller K, Schiffer M, Hoffmann A; (2008) “Developing and testing a diagnostic Probe for Grape Phylloxera Applicable to Soil Samples” Entomological Society of America, 0022-0493/08/1934-2943.
“Proceedings of the international Symposium on Grapevine Phylloxera management”, Jan 2000, Melbourne Australia GWRDC
Powell K, (2003)“Targeted Phylloxera Options”, Final Report GWRDC.