Black Chaff, Melanosis, Glume Blotch: The Causes of Darkness on Wheat Heads at Harvest

It may have an ominous sounding name, but black chaff is rarely a cause for major concern in wheat, says a crop pathologist with Manitoba Agriculture.

Black chaff is one of several wheat disorders that will catch a grower’s eye at harvest due to the dark colour and discolouration that appears on wheat heads.

Wheat heads affected by melanosis (photo courtesy MAFRD Crop Diagnostic Lab)
Wheat heads affected by melanosis (photo courtesy MAFRD Crop Diagnostic Lab)

As Holly Derksen explains in the interview below, the symptoms of black chaff usually only show up when the grain is ripe.  The same pathogen causes what’s known as “bacterial leaf streak” earlier in the growing season.  Black chaff can be confused with melanosis (which is sometimes caused by copper deficiency), glume blotch, or even fusarium head blight.

Although they may appear similar, the causes of each of these disorders are completely different; black chaff is caused by bacteria, melanosis is abiotic and glume blotch is a fungal disease, notes Derksen.

If you can’t see the embedded player, click here to listen to Holly Derksen’s interview with Kelvin Heppner.

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