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What is it?
Karnal bunt is primarily a disease of wheat used to make bread, but also affects durum wheat. It is caused by the fungus Tilletia indica. Flour made from infected wheat is unfit for human consumption because it has an objectionable smell and taste.
Where is it found?
Karnal bunt was first noticed in northern India in 1930. It prefers cool, humid conditions and has since spread to other parts of Brazil, India, Pakistan, Afghanistan, Nepal, Iraq, Iran, Mexico, South Africa and southern and eastern parts of the United States.
What are its effects?
Signs of karnal bunt are hard to detect in the field because only a few seeds on each head are attacked, but symptoms become more obvious in processing. All or part of the grain is replaced with a powdery mass of dark spores that emit a strong, fishy odour.
Harvesting shatters infected grains, releasing the spores and leaving behind a broken, hollow grain. Spores can spread over long distances by wind and survive in the soil or on stored seed for up to five years.
What’s the risk to Australia?
Australia has suitable conditions for karnal bunt and the disease could have a major economic impact on our wheat-growing industry, severely disrupting grain exports. To manage the risk of this disease, Australia has strict quarantine regulations for imports of new wheat varieties or breeding lines for sowing.
Because karnal bunt can survive in soil and on agricultural machinery, Australia also requires that imported agricultural machinery must be cleaned. Feed meals, seeds and fertilisers that may have been handled in the same transportation system as infected wheat must also be free of wheat seed contamination.
24 Apr 2012