Fungal Plague Could Threaten Global Wheat Supply

  • Published on February 19th, 2009


In Kenya there’s a quiet disaster happening, and it’s reaching epidemic proportions. Stem rust, a wheat destroying fungal infestation that was ‘wiped out’ in the West half a century ago, has resurfaced in Africa and already transmitted its fatal pathogen as far as Iran.

So far, agronomists are unable to control its spread and have no clear line on the only alternative treatment method: finding resistant varieties of wheat and breeding them – fast.

The destructive potential of stem rust follows on actual food riots in Mexico and Africa in 2008, and lays bare how fragile the food supply is in poorer nations. It should also make us stop and think about the way our own staple foods could be vulnerable – if this stem rust travels as far as America and Europe, where monoculture is almost universal, and if our wheat varieties are susceptible, there could be no bread. Not expensive bread, or rationed bread. Simply – no bread.

Stem rust fools the eye and spreads like wildfire

Stem rust is pernicious because for quite a long time the plant looks normal – only when the wheat is husked does it become clear that there are no seed kernels in the empty heads of wheat, and by that time, it’s too late to stop the fungus spreading further, on the wind, on car tyres and on clothing and shoes, tracked from one field and farm to another.

And while we could adapt for a week or a month, how do closely packed communities manage when a staple supply is removed from their shops? They hoard if they can afford it, and they riot when even hoarded stocks run out.

Back in 1999 the first signs of danger emerged – plants that had been bred to be completely free of susceptibility to stem rust were succumbing to it. The pathogen had evolved past the wheat’s resistance thresholds and it’s now reckoned that over 80% of commercially grown Asian and African wheat could be at risk.

Winter postpones the problem – but doesn’t solve it

Cold winter areas like Northern Europe and the Northern states of America have a certain, very limited, degree of protection from the epidemic, because cold winters inhibit transmission – the fungal spores die at low temperature, but in the previous stem rust epidemics, crops were still destroyed by spores that overwintered in the south and travelled north on spring winds.  The race is on in labs around the world, trying to find resistant strains of wheat as the pathogen leapfrogs around the world. To date, after nine years of research, no reliably resistant variety has been found … it’s only a matter of time, scientists say, but they can’t guarantee that they will find a solution before the problem arrives in our wheatfields.

French wheatfield courtesy of Meanest Indian at Flickr under a creative commons licence

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