Pea leaf weevil continues to expand its range across the Prairie provinces, with some of the highest recent feeding levels now recorded in western Manitoba.

“It has moved quite far north and also quite far east,” Vankosky said.

Prairie Pest Monitoring Network surveys show that in 2025 some of the highest feeding levels were recorded in western Manitoba, in areas where populations were likely high enough to cause economic damage in field peas and faba beans.

The most recent monitoring map suggests the pest’s Prairie-wide establishment is now complete, with detections reaching the Ontario border.

Life cycle and what to watch for

Pea leaf weevil produces one generation per year, with adults active in spring and again in late summer. In spring, adults move into pea and faba bean fields and feed along leaf margins, leaving distinctive crescent-shaped notches. While the foliar feeding is visible, the more serious damage happens below ground.

Larvae feed on root nodules, reducing the plant’s ability to fix nitrogen and affecting both yield and seed quality.

Weather plays a role in population dynamics. Wet conditions tend to favour survival in the soil stage, while drought can limit larval development.

Monitoring focuses on counting feeding notches on seedlings between the second and sixth node stages. Nominal thresholds are 30 per cent of field pea seedlings showing damage to terminal leaves and 15 per cent in faba beans.

Management options remain limited

Management options remain limited for pea leaf weevil. Although foliar insecticides are registered, recent work in southern Saskatchewan found no yield benefit from applying a foliar spray.

Seed treatments can offer protection, but they must be applied at planting, before growers know what adult pressure will be in a given field. Evidence suggests seed treatments can protect yield, but the benefit depends on weevil density.

“There is no strong evidence that foliar insecticides protect against yield loss,” Vankosky said.

That puts growers in a difficult spot, particularly in areas where the pest is still expanding and pressure can vary widely from year to year.

“If you are planning to plant peas or beans in an area that had very high populations last year, you might want to consider applying the seed treatment,” she added.

Researchers are also studying alternatives to insecticides. Beneficial insects such as ground beetles have shown some ability to feed on pea leaf weevil eggs and adults, and work is underway to better understand how much natural impact enemies may have on populations.

Trap cropping — planting early strips of peas or faba beans to attract and concentrate adults — is also being explored, though it requires further field-scale testing.

With the insect now established across all Prairie provinces, Vankosky encouraged growers to monitor fields closely in early spring and consult the local survey maps produced annually by the Prairie Pest Monitoring Network.

Key takeaways for prairie growers

• Pea leaf weevil is now established across all Prairie provinces and has been detected as far east as near the Ontario border.
• In 2025, some of the highest recorded feeding levels were in western Manitoba — including areas with likely economic damage.
• Foliar insecticides do not protect yield. Seed treatments at planting are the main management option.
• Economic thresholds are 30 per cent of pea seedlings with terminal leaf damage, and 15 per cent for faba beans.
• Monitor Prairie Pest Monitoring Network survey maps each spring for local population updates.

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That north-south line cleaves North America in two from Mexico to Manitoba, as first noted in 1978 by explorer John Wesley Powell, who called it the boundary between the humid East and the arid West.

Now scientists are looking how this partition has played out so far, and what the future may hold. They confirm that the divide has turned out to be very real, as reflected by population and agriculture on opposite sides.

They say also that the line appears to be slowly moving eastward, due to climate change and will almost certainly continue shifting in coming decades, expanding the arid climate of the western plains.

“This concept of a boundary line has stayed with us down to the current day,” said Richard Seager, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. “We wanted to ask whether there really is such a divide, and whether it’s influenced human settlement.”

Powell noted correctly that the western plains are dry in part because they lie in the rain shadow of the Rocky Mountains. Seager’s team identifies two other factors. In winter, Atlantic storms bring plenty of moisture into the eastern plains, but don’t make it far enough to moisten the western plains. In summer, moisture from the Gulf of Mexico moves northward, but that also curves eastward, again cheating the west.

Now, the researchers say, warming climate appears to be pushing the divide east. In the northern plains, rainfall has not changed much, but higher temperatures are increasing evaporation.

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I took a look at the monthly data for the major centres across the Prairies in regards to temperatures and precipitation over the last three months. Below are the results. I have ranked or ordered the results in several different ways.

The first table below on the left is ranked by overall mean or average temperatures during May, June, and July. Looking at the table you can see that overall, Saskatchewan was the warmest, followed by Manitoba and then Alberta.

The second table on the right (see above) reorders our locations, based on how much each site’s average temperature differed or deviated from the long-term average temperature for that location. Looking at this table we see that Alberta is now the warmest region, with Saskatchewan coming in second and Manitoba last.

The third table below on the left looks at precipitation and I have ordered the data by the total amount of precipitation that fell at each location. Looking at the data you can see that the regions that saw the most rainfall were the more northern regions of the agricultural Prairies, with southern Alberta and southern and central Saskatchewan seeing the least precipitation.

Reordering the data on the right (see above) to show rankings comparing total precipitation to the long-term average for each location, or how much each station differed from their respective average, you can see that Regina has been remarkably dry compared to average, with a deficit of 137.5 mm of rain. Calgary also comes in very dry compared to the long-term average. The order then changes up a little bit with both Brandon and Winnipeg, which were higher on the list of total rainfall, now coming in as the next driest compared to average.

Hopefully this helps to shed a little bit of light on what has been going on weather-wise across the Prairies over the last few months. I also hope that looking at the data in a couple of different ways helps to put things into perspective. Regina, no matter how you look at it, has had a hot and dry last three months. Calgary, while dry, was not that warm overall, but compared to average it was the warmest region on the Prairies. So, when it comes to weather, pretty much everything is relative. What is warm in one place can be downright hot in another.

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Arctic high pressure building in behind the strong eastern low will keep our skies mainly clear to begin this forecast period. Along with the clear skies will come cold temperatures, with highs struggling to make it to around -15 C. Depending on snow cover, overnight lows will be in the -20 to -25 C range, with the coldest temperatures occurring where the snow is the deepest.

Confidence in the weather models is not that high going into the weekend and beyond, as they try to get a handle on what is looking to become a more active pattern. We could see some snow and blowing snow on Friday as a clipper system moves rapidly across the southern Prairies. Another arctic high will drop down behind this low, bringing clear skies and more cold weather for the weekend. This high will quickly move off to the southeast over the weekend and by early next week we should begin to see temperatures moderate as the winds become more southerly.

We’ll have to watch for the possible development of a fairly strong storm system over the central U.S. around the middle of next week. Currently, the models are keeping most of the energy from this system to our south as arctic high pressure lingers to our north. Once again, confidence in this part of the forecast is low, but it does bear watching.

Usual temperature range for this period: Highs, -14 to 1 C; lows, -24 to -8 C.

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The large low over Hudson Bay formed as expected and did drag a cold front across our region last weekend, bringing with it the coldest weather so far this fall/winter. Now, this is when the forecast changes. Instead of the forecast arctic high diving southeast into northern Ontario, a strong area of low pressure off in the Pacific set up a pattern that is allowing this high to drop straight south through Alberta and western Saskatchewan.

This will place us on the eastern side of the high, which will keep us in moderate northerly winds, cold temperatures and, at best, a mix of sun and cloud during the day along with the odd flurry. Daytime highs will only be in the -5 to -10 C range, with overnight lows around -15 C. Depending on the exact location and strength of the high, the best bet will be that western areas will see more sun than clouds, while eastern areas will struggle to see the sun.

This pattern of an eastern trough and western ridge, somewhat reminiscent of last winter, looks as if it will continue for at least the next couple of weeks as the models show the eastern trough of low pressure deepening and retrograding to the west a little bit. At the same time a second arctic high is forecast to drop southward, bringing with it more cold air. Luckily, at this time of the year, weather patterns tend to switch really rapidly, so let’s keep our fingers crossed.

Usual temperature range for this period: Highs, -7 to 4 C; lows, -16 to -4 C. Probability of precipitation falling as snow: 88 per cent.

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Overall, the forecast for the next couple of weeks looks to be pretty good. Confidence is actually fairly high as the weather models have been relatively consistent from day to day with their forecasts. This forecast period will start off mild, when an area of low pressure pulls up nice mild air as it moves in from the West. This low will move through on Thursday and Friday and it looks like most of the precipitation with this system will be in central and northern regions of Manitoba.

Things will start to clear out Saturday, but it will be a little on the cool side as we’ll see a fairly strong northerly flow behind the low. A ridge of arctic high pressure is then forecast to begin building southeastward starting on Sunday. This should bring us mainly sunny skies on Sunday and Monday, with high temperatures expected to be around the middle of the usual temperature range for this time of the year.

As the high drifts to our southeast, it’s forecast to strengthen and stall out over the Great Lakes. This will place us in a warm southerly flow as the arctic air modifies and warm air is pulled up from the southern U.S. It looks like it will be sunny for most or all of next week, with temperatures getting warmer each day. I wouldn’t be surprised if highs end up exceeding the top end of the usual temperature range for this time of the year by next Tuesday or Wednesday.

Usual temperature range for this period: Highs, 4 to 16 C; lows, -5 to 4 C. Probability of precipitation falling as snow: 25 per cent.

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This forecast period begins with us still dealing with the large low wobbling over northwestern Ontario. We will see partly cloudy days along with northwesterly winds as we remain on the back side of the low. This will keep temperatures on the cool side, with highs expected to be around 10 C. Overnight lows will be a little trickier and will depend on cloud cover. If skies are clear at night, we’ll see lows in the -2 C range; otherwise, lows will be around +3 C. This low looks as if it will weaken and finally move off to the east by about Friday.

Over the Thanksgiving long weekend, the weather models show a ridge of high pressure building to our southeast and extending back into the southern Prairies. This should bring mainly sunny skies along with slightly warmer temperatures, and highs expected to be in the 10 to 15 C range. A large area of low pressure is also forecast to begin moving in off of the Pacific sometime on Sunday. This likely means we’ll see increasing clouds with the chance of showers on Monday. A southerly flow ahead of this system could also mean we’ll see fairly mild temperatures Monday, but that will depend on the timing and amount of cloud cover and any precipitation.

Looking further ahead, the models show this low deepening and stalling out to our east, meaning a return to cool unsettled weather.

Usual temperature range for this period: Highs, 8 to 17 C; lows, -4 to 5 C.

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For this forecast period we have to contend with two different areas of high pressure. The first high is another surface-based arctic high, expected to slide southeastward during the week. This high should take a much more easterly track through northwestern Ontario. At the same time we’ll see an upper ridge of high pressure building to our west try to move eastward. It will be a tough call as to which high will have the biggest influence on our weather.

It now looks like we’ll see a mix of sun and clouds from Wednesday to Friday as cold air remains in place in the upper atmosphere. Temperatures will slowly warm as the week goes on, with highs expected to be in the low 20s and overnight lows around the 5 C mark. We could see a bit more clouds along with the odd shower on Friday as a weak low slides through.

Over the weekend and into the first part of next week the western upper ridge should finally move in, bringing mainly sunny skies along with high temperatures in the low to mid-20s. Beyond this, the weather models show a fairly strong area of low pressure moving across the northern Prairies. This low will likely drag a cold front across central and southern Manitoba sometime on Wednesday, bringing a short shot of cooler air.

Usual temperature range for this period: Highs, 12 to 22 C; lows, 1 to 9 C.

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But be forewarned, while reading through it doesn’t leave one with any overriding sense of panic, neither does it leave one feeling particularly comfortable with our farming system as we know it today.

The document represents the best guesses of 23 scientists representing various fields of expertise presented at the Alberta Institute of Agrologists conference last month. As a forward-looking document, it offers a frank look at where we are today on the Prairies and lays out some of the challenges that could change agriculture’s path into the future.

As can be expected, there are some positives but also negatives in store. The Prairies are no stranger to a variable climate, but it is the intensity of the various hot, cold, wet and dry extremes that is of concern as well as the changing disease, weed and pest cycles.

More land might become farmable as the mean temperature rises and growing seasons become longer, but increased moisture contraints may limit the productive capacity of land already being farmed.

Instead of becoming the new Iowa as some have suggested, it might be more realistic to think South Dakota instead, these academics suggest. Corn and soybeans are making inroads into some areas, particularly the eastern Prairies, but the dominant three crops on the Prairies — wheat, barley and canola — won’t be pushed from their pedestals.

On balance, a warmer Prairie climate doesn’t bode well for the pollinator community, largely because the stressors such as the varroa mite will be harder to control. Invasive species, such as the Africanized killer bees, are expected to make their way northward.

The weed spectrum will become more complicated. Winter annuals are already becoming more of a problem. As well, weeds that have developed resistance to one or more herbicides, including glyphosate, in the U.S. are moving northward. On the upside, the ability to grow a more diverse range of crops, including winter crops and warm-season crops, increases a farmer’s ability to employ integrated weed management.

• From the Grainews website: Diversify rotations to slow resistance

Fusarium head blight is expected to thrive in the changing Prairie climate; the mycotoxins associated with it are shifting too. Expect new pests such as new types of nematodes, especially if farmers develop favourites and follow tight rotations.

On the livestock front, warmer winters could reduce overwintering costs for cattle producers, the majority of which have switched to winter grazing systems — except that the increased frequency of extreme weather could create shocks that threaten herd health. Anthrax and liver flukes may become more common.

There will be impacts on grain storage, handling and transportation given the warmer temperatures and increased likelihood for dramatic swings in temperature. Consider this spring’s warning from the Canola Council of Canada on the potential for spoilage of canola in storage due to a quick move to warmer temperatures.

Ports such as Churchill will likely see a longer shipping season, but the railway line servicing it will be affected by the melting permafrost.

How will the world trade be affected because of changing supply and demand and the surge of bilateral trade agreements in the absence of a world trade deal? Can the insurance schemes in place keep up? Is the industry prepared to address the challenge of adaptation.

AAFC scientist Henry Janzen outlines the need for a comprehensive adaptation strategy that looks beyond the economic opportunities and one that can “envision the range of unfolding possibilities for future lands, and to devise measures that will be robust across a long time, even in the event of certain surprises.

“Ironically, some of the best insights toward this future perspective may be found in the past, by asking: Which metrics have survived the tumultuous changes of the past century or so? Some of these, such as soil carbon, ecosystem nutrient balances, diversity of farming systems (including livestock) might well be melded into future metric systems.”

Prairie agriculture has been in a dynamic state of flux ever since the Selkirk settlers arrived here just over 200 years ago, so it comes as no surprise that it must continue to evolve. In today’s context however, it’s important farmers don’t lock themselves so tightly through investments and contracts they can’t continue to adapt as their environment changes.

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“There are some concerns with pasture recovery and just starting up the season next year,” said Trevor Hadwen, agro-climate specialist with Agriculture and Agri-Food Canada.

“In terms of native pasture, the dry fall doesn’t allow the recharge of the soil moisture, which doesn’t allow the plants to prepare as well for the winter as they normally would.”

The biggest area of concern is a region starting in central Alberta and stretching into Saskatchewan, he said.

There are some dry regions in Manitoba as well, but many areas in the south and southwest received some good precipitation this fall.

“The southwest (region of Manitoba) has received quite a bit of rain, getting a few of those storms that were popping up from North Dakota,” Hadwen said.

Though the soil is too dry in Alberta now, it’s likely that things will improve in spring, said Drew Lerner of World Weather Inc. in Kansas.

“We’ve had some snow events already (in Alberta) which helped to pad the dryness a little bit and it kind of suggests that maybe we’ll see some improvement in the spring,” said Lerner. “A lot of the snow that fell will help to keep frost out of the ground, so when we do get into the spring thaw, the moisture will go into the ground fairly quickly.”

It’s still a wait-and-see kind of situation in Saskatchewan, though Lerner said he expects average snowfalls during the first half of winter across Western Canada, and that should keep winter wheat crops covered, he said.

“I think in general, the crop will probably be in fairly good shape,” he said. “There will be some very impressive bouts of cold that will occur, but I think we’ll have sufficient snow on the ground to take care of that. So, when it comes to the spring, we should at least get a fair start to the season.”

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