Shadows of the Irish Famine
- July 29, 2009 11:08 AM |
- By Kevin Yarr
By Kevin Yarr, CBCNews.ca
The disease that led to the crash of the potato harvest in Ireland in the 1840s still haunts farmers in the 21st century.
The fungus first appears on the potato leaves. (CBC)
Late blight is a fungus. Its spores spread on the wind, settling on the leaves of potato plants (it can also affect tomatoes). The leaves turn black, and the infection spreads down into the potatoes, rotting and leaving them inedible.
Prince Edward Island has been having the same damp, cool summer weather as many other parts of the country. It's not very good for tourism, and it's not good for potato farming either. Being a fungus, late blight thrives in this weather. The Island has been fortunate in recent years with late blight cases being counted in single digits. This year there have already been 30.
It's a problem across the eastern half of the continent.
Unlike what happened in the 19th century, that doesn't mean we're facing a failure of the potato crop. Modern agricultural techniques can control the spread of blight, but those controls come at a price.
First there is the literal cost. When late blight is in the air, farmers need to spray fungicides regularly - every three or four days. They spray this frequently because the fungicide is only effective if it is covering the leaf. At this time of year the plants are growing quickly, and the new leaves need to be sprayed. All that fungicide is expensive.
Then there is the environmental cost. Fungicides to control late blight are the most common pesticides sprayed on potato crops.
Researchers with Agriculture Canada are working on better ways to control late blight. They're cross-breeding ancient potato varieties from Peru, which have high late blight resistance, with commercial varieties in the hopes of creating commercial breeds that can resist the fungus.
Unfortunately, currently some of the most popular commercial varieties, such as Yukon gold, are highly susceptible to late blight.
Until research finds a better answer, fungicides - and hoping for some dry, hot weather - will remain the most common defences against late blight.
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