Hot, dry conditions drove down insect and disease pressure in 2018

By and large, producers didn’t see as much insect damage or disease loss this year

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Crop yields in Alberta took a hit this year because of the hot, dry conditions — but the blow wasn’t as big as it could have been, thanks to decreased disease and insect pressure.

“Across the province, we’re trending close to the five-year average, and the lack of disease and insect pressure may have helped yields from going down even further,” said provincial crop specialist Mark Cutts.

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Diseases tend to flourish in cool, moist conditions, so in a year like this one, it’s not surprising that disease pressure was down, said Cutts. But the opposite is typically true for insects.

Not so this year.

“Warm, dry conditions generally lead to insects developing rapidly, allowing their populations to build up,” said Cutts. “But it wasn’t a really big year for insects, which is interesting.”

Certain pockets of the province experienced some insect pressure, but the infestations weren’t particularly severe this year, he said. Flea beetles were a concern in central Alberta early in the growing season, and bertha army worm caused some damage in one area of the central Peace.

While pea leaf weevil and wheat stem sawfly numbers built a little over the summer, the damage this year wasn’t as significant as in past years. Wheat midge, diamondback moth, and lygus bugs prompted some spraying across the province, but overall caused very little damage. Southern Alberta saw most of the insect pressure in the province because of the drought, so cabbage seed pod weevil and grasshopper numbers were up south of Highway 1.

But overall, “it was a very quiet year” for insect pests, said Cutts.

It’s the same story with crop diseases, said federal research scientist Kelly Turkington.

The major players — fusarium head blight in cereals, clubroot in canola, and root rots in pulse crops — caused problems in some areas, and may have even spread, but disease severity was generally down because of the dry conditions.

“Across the board, disease levels were relatively low, but occasionally, there would be certain fields that might have moderate levels of disease, particularly in southern Alberta,” said Turkington.

“In those cases, some sort of localized thundershower or rain systems likely contributed to disease development. So producers may have noticed some symptoms in a number of fields, but in general, the severity levels were low.”

And that seemed to help crop yields in most of the province, he said.

“Given the lack of disease development, there shouldn’t have been an issue in terms of yield and grain filling. The plots and fields we were in didn’t look too bad, given the conditions.”

But even if disease pressure didn’t hurt yields as much this year as in previous years, fields may still have had low to moderate disease levels — and any of that infected debris will go back into the soil as inoculum for next year.

“That infected plant material could still be in the field and could potentially cause issues if that field is planted back to a host crop in 2019,” said Turkington. “Probably one of the best strategies is to simply extend your crop rotation. Try to have as many years as a non-host between your crops.”

Risk maps will also help producers stay on top of diseases going into the next growing season, Turkington added.

“We’re starting to see more and more availability of risk maps — tools that can be used by producers to indicate a potential risk that is developing,” he said.

Risk maps are also available for insect pests, said Cutts. The results from the 2018 insect survey should be out in the next couple of months and will help producers manage insect pressure going into the next growing season.

“If there were some large populations and the females ended up laying a lot of eggs, there’s the potential for those areas to have some significant population numbers for next year,” said Cutts.

“If you’re in an area where they’re indicating there are high numbers of an insect pest, that’s your first indicator that there’s something you need to be aware of next spring when you’re out scouting.”

About the author


Jennifer Blair

Jennifer Blair is a Red Deer-based reporter with a post-secondary education in professional writing and nearly 10 years of experience in corporate communications, policy development, and journalism. She's spent half of her career telling stories about an industry she loves for an audience she admires--the farmers who work every day to build a better agriculture industry in Alberta.



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