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Herbicide Resistance Across the Prairies

Herbicide-resistant weeds are becoming a common problem for Prairie farmers, limiting their options for chemical weed management and increasing the importance of non-chemical management strategies.

Charles Geddes, a research scientist of weed ecology and cropping systems for Agriculture and Agri-Food Canada, says that herbicide resistance has been on the rise globally.

“It’s a growing problem across the country, and it’s not just happening in Canada,” says Geddes.

“It’s a global issue and one that I think farmers will have to deal with every year. It has been increasing in the Prairies and in Eastern Canada. Just to put the problem into perspective, in Canada, we’re sitting in third place for having the greatest number of herbicide-resistant weed species globally.”

Geddes notes that approximately 70 per cent of fields surveyed in the Prairies have at least one type of herbicide-resistant weed, and that this trend has largely arisen in the past two decades.

Rob Gulden, a professor in the Department of Plant Science at the University of Manitoba, says that surveys, which are conducted across the Prairies on approximately five-year cycles, have been finding new types of resistance in different weeds.

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Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

Video: Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

A new peer reviewed study looks at the generally unrecognized risk of heat waves surpassing the threshold for enzyme damage in wheat.

Most studies that look at crop failure in the main food growing regions (breadbaskets of the planet) look at temperatures and droughts in the historical records to assess present day risk. Since the climate system has changed, these historical based risk analysis studies underestimate the present-day risks.

What this new research study does is generate an ensemble of plausible scenarios for the present climate in terms of temperatures and precipitation, and looks at how many of these plausible scenarios exceed the enzyme-breaking temperature of 32.8 C for wheat, and exceed the high stress yield reducing temperature of 27.8 C for wheat. Also, the study considers the possibility of a compounded failure with heat waves in both regions simultaneously, this greatly reducing global wheat supply and causing severe shortages.

Results show that the likelihood (risk) of wheat crop failure with a one-in-hundred likelihood in 1981 has in today’s climate become increased by 16x in the USA winter wheat crop (to one-in-six) and by 6x in northeast China (to one-in-sixteen).

The risks determined in this new paper are much greater than that obtained in previous work that determines risk by analyzing historical climate patterns.

Clearly, since the climate system is rapidly changing, we cannot assume stationarity and calculate risk probabilities like we did traditionally before.

We are essentially on a new planet, with a new climate regime, and have to understand that everything is different now.