Providing practical information to help you protect your farm from biosecurity risks

Something fishy about mock Karnal bunt incursion

June 5, 2015
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Grain showing Karnal bunt infection symptoms. Image: PaDIL

Over the next year, there will be three biosecurity ‘fire drills’ run on one of the most potentially damaging pests of grains. The three simulation exercises will look at different aspects of an incursion of a fungal pest of stored grain called Karnal bunt (Tilletia indica).

Dr Stephen Dibley, Plant Health Australia’s Program Manager, Training and Biosecurity Preparedness, said the simulation exercises will look at how elements of the supply chain interact, including growers, industry bodies, bulk grain handlers and transporters.

“Mock incursions like this are a good way to assess any gaps in a response plan before we have to face with the real thing,” said Stephen.

While an infected crop may show some decline in yield, the main impact is on the quality of grain.

If Karnal bunt were to be detected in Australia, because many countries have import restrictions on this pest, access to over 45 international grain markets is likely to be restricted and the value of Australian grain would significantly decrease.

The hosts for Karnal bunt are wheat, durum and triticale. It is difficult to detect in the field: symptoms on the growing plant are not always conspicuous and usually only a few seeds in each head are affected. Affected seed are blackened with spores, can be easily crushed and have a distinctive fishy smell.

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Karnal bunt affected wheat head. Image: Ruben Durán, Washington State University, bugwood.org

It may be confused with common bunt, which is found in Australia and which looks and smells very similar. However, common bunt affects entire heads and seeds of a cereal plant. Karnal bunt is also similar to loose smut, flag smut and black point.

“Because of its potential impact, and because symptoms can be hard to detect and distinguish from these other pests, producers need to be particularly vigilant about surveillance to detect it early,” added Stephen.

“Movement restrictions placed on grain consignments to prevent the spread of the disease could also affect livestock producers further along the supply chain such as feedlot beef, pork and poultry producers.”

“Even short term restrictions on the movement of grain could cause depletion of feed supplies for animals,” advised Stephen.

While animals can eat grain that has a low level of contamination (about 3 per cent) and the spores can be inactivated by heat treatment, the value of animal feed stock is much lower than usually obtained for export grain and growers would suffer severe losses.

Affected grain would also be unsuitable for milling to produce flour for human food products.

Soil becomes infected when rain falls on infected plants or developing ears, and when contaminated grain is harvested. Spores are small and long lived, surviving in grain stores, soil (possibly years, depending on environmental conditions) and cereal trash. Spores can be spread between paddocks by wind and water, on machinery or other equipment.

To protect your farm, check stored grain frequently for the presence of new pests and unusual symptoms. Make sure you are familiar with common grain pests so you can tell if you see something different, and report it to the Exotic Plant Pest Hotline 1800 084 881.

Karnal bunt fact sheet