Blueberry rust: declared pest

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Blueberry rust is a plant disease caused by the fungus Thekopsora minima, which affects a range of plants in the Ericaceae family, including blueberries, cranberries and rhododendrons.

This pest has been reported in Europe, Argentina, Asia, Mexico, Canada and the United States of America. In Australia, it has been present in parts of New South Wales and Queensland for many years.

Blueberry rust is not known to occur in Western Australia. Early detection and reporting of blueberry rust will help protect the Western Australian blueberry industry.

WA growers and members of the public who suspect the presence of Blueberry rust should contact the Department of Agriculture and Food, Western Australia on 1800 084 881.

What plants are affected?

Blueberry rust is a fungal disease of a range of plants in the Ericaceae family, including the genera: 

  • Vaccinium spp. (blueberries and cranberries)
  • Gaylussacia spp. (huckleberries)
  • Rhododendron spp. (azalea)
  • Lyonia spp.

Conifer hemlocks (Tsuga spp.) are the alternative hosts which the rust requires to complete its lifecycle in colder climates. These species are believed to be uncommon in Australia, but in mild climates such as Australia's the rust can survive without completing its life cycle.

To date, blueberry rust has only been reported on blueberries (Vaccinium spp.) in Australia. Southern Highbush varieties and their cultivars are more susceptible to the disease than other varieties.

What do I look for?

The initial symptoms of blueberry rust are reddish spots on the upper surfaces of young leaves. These lesions darken with age, often surrounded by a yellow halo, and may merge as the disease progresses. Infected leaves may curl.

On the undersides of the leaves, yellow pustules develop to release spores capable of infecting other leaves and spreading the disease.

In severe cases, leaves can turn brown and drop prematurely. Rust spores may be found on other parts of the plant (such as fruit and stems) if they become dislodged from the pustules.

How does it spread?

Blueberry rust produces spores during five life stages. The disease can overwinter on evergreen blueberry leaves in milder climates, but is more prevalent in warm, wet conditions.

New pustules can be produced and release spores every 10-14 days, with more rapid spore production occurring under favourable climatic conditions. The optimum temperature for spore production is around 21°C, but new infections are unlikely when the temperature is over 30°C.

The millions of spores released from the pustules are very easily and quickly transported by wind (up to several hundred metres), but can also be spread via infected plants and fruit, packaging, equipment, clothing and hands.

The spores are able to re-infect the original host plant as well as other blueberry plants and other host species.

What damage can this disease cause?

Defoliation of affected plants reduces vigour and, in the following year, crop yield. Serious defoliation may lead to the death of susceptible cultivars.

What do I do if I find it?

WA growers and members of the public who suspect the presence of blueberry rust should contact the Department of Agriculture and Food, Western Australia’s Pest and Disease Information Service (PaDIS) on 1800 084 881. They can also send plant samples to AGWEST Plant Laboratories.

When sending samples, package the leaves between sheets of absorbent paper, such as newspaper, to prevent them getting crushed in transit and enter the locality where collected, date and collector’s contact details. It is important not to post specimens on a Thursday or Friday. This avoids deterioration while in transit over the weekend.

Farm biosecurity measures

DAFWA advises growers to follow farm biosecurity measures, which include restricting farm visitor access, using footbaths, and cleaning and disinfecting tools and machinery.

Refer to Farm Biosecurity for more information on farm biosecurity measures.

More information

For information on the management of blueberry rust, refer to the Victorian Department of Environment and Primary Industries website.

 

Page last updated: Wednesday, 22 July 2015 - 12:54pm