Farmers were celebrating some of their first real rainfalls of the season in June, but agrometeorologists and agronomists aren’t quite ready to break out the party hats.
Why it matters: Social media was full of jubilant rain gauge pictures last month, but agronomists say the damage to yield potential has already been done for some crops, but unless there’s more rainfall it’s just a temporary relief.
Parts of the province, particularly in western Manitoba, were at average or had even exceeded average precipitation for May and June, according to ag weather data from the province, although the Interlake and northeastern agro-Manitoba were still reporting less than 60 per cent of their normal rain.
Farmers have seen sporadic storms in the weeks since the end of May, a point when many crops were in, or soon to be in, dire straits. The season’s dry streak broke, with parts of the northwest and central Manitoba reporting over 50 millimetres of rain June 8-10. Other storms followed, including in the southwestern corner of the province, with up to 39 millimetres between June 21-27.
But while, at first glance, the rain map has helped close the moisture gap producers found themselves in this spring, meteorologists argue that the timing of those rains may make pure accumulation numbers deceptive.
The key word, according to Manitoba Agriculture and Resource Development’s Dane Froese, is ‘if’ producers saw rain.
While rain looks widespread on the map, in reality Froese noted that rains have been patchy largely coming from intense but localized storms, not widespread rains.
“The farmers who benefited from the thunderstorm lottery might be happy and might be in better condition than their neighbours a few miles away, but the overall area that the rainfall does affect is limited,” he said.
Such sudden rainfall also has more chance of running off than infiltrating, he noted, while the benefit from that rain may be coming right back out in transpiration, even if water does move into the soil.
“Because our crops are in such desperate thirst for water, the heat turns back on the next day and those crops pump out perhaps even as much rain as they received,” he said. “For instance, wheat is using about half to three-quarters of an inch of water per day in some instances right now.”
Crops have improved in areas that saw rain, according to the June 29 provincial crop report, although the same report noted that drought stress has led to many crops maturing more quickly than normal and many crops are atypically short.
Bruce Burnett, director of markets and weather information with Glacier FarmMedia, also noted the disparity.
Rain “has helped the situation in some regions, but other regions have not got those rains,” he said, singling out the Interlake and parts of eastern Manitoba and into the Red River Valley as still largely dry.
Rains have also not kept harvest expectations from falling, he said, describing 2021 as one of the most challenging seasons of the last decade.
“If we were looking for average to above-average yield potential this year, I think that just isn’t in the cards for us,” he said.
“I’m thinking we’ve had enough difficulties this spring that it’s going to be very, very difficult to look at an average yield,” he added.
Outside of drought, which delayed emergence in some cases, crops faced a see-saw of temperature conditions in late May and early June, with extreme heat warnings coming only days after late frost.
Fields are stagey, Froese noted, and he has observed fields where parts are in flower, while others have yet to break past the fourth- or fifth-leaf stage.
Unless planting was delayed, rains likely came too late for crops that set yield potential early, Burnett said — something reflected in reports from cereal growers, who say they are expecting to take less to the bin this fall. Rains may well have been timely for soybeans, however, he noted, while canola faced additional challenges from heat in early July.
High grain prices may help add to the financial buffer, even if yields fail to impress, although Burnett noted the disappointment of missing out on what could, otherwise, have been a bumper year for farmers at the bank. And at the same time, he said, there are producers expecting far more than the modest yield hit that might be cancelled out by higher prices.
Cereal yield potential has already taken a hit, even if the province gets consistent rains for the rest of the season.
Maximum yield is set roughly by the fifth-leaf stage, according to Rejean Picard, cereals specialist with the province. Fields that got moisture in June likely benefited, Picard said, but noted that some fields were more fortunate in that regard than others.
Future rain would help maintain yield potential for fields already headed out, he said, “but there’s already been some damage kind of baked in, you might say, into the stress that some of those crops have suffered.”
Kernels per head, for instance, may be reduced.
“I’ve seen some crops that have headed out or are very close to headed out that have definitely much smaller heads than you would expect from a wheat crop,” he said. “Even if there are some tillers that might emerge from that one, it’s not going to compensate for what’s been lost already.”
Despite an easy winter, spring was unkind to winter cereals. Those crops went into the soil during 2020’s also dry fall, Picard noted and added that many of those plants only managed a few leaves before winter, or did not emerge.
Picard believes rain did come in time for those crops. Fall rye fields have looked “OK,” he said, although he added that he also heard of other producers shifting winter cereals to greenfeed due to low yield potential.
Alex Griffiths, agrologist with Ducks Unlimited (a major partner of the Western Winter Wheat Initiative), says three of the 20 fields in his program had to be terminated due to winterkill. Those, he added, were largely less hardy varieties, or had agronomic practices less conducive to winter survival.
“With the lack of rain, things are a little on the thin side, but I don’t think that any crop I’ve seen looks excellent,” he said. “It’s all going to be fine, but I don’t know if anyone’s going to be hitting 100-bushel winter wheat this year, by any means.”
After a spring typified with dry planting conditions, high winds and extreme flea beetle pressure, canola acres likely caught a break with June rain.
“Most canola fields put on a pretty good growth spurt, even if they did look a little ugly,” Froese said.
Justine Cornelsen, agronomist with the Canola Council of Canada, agreed.
“It definitely looks a lot better than it did in the beginning of June,” she said.
The crop progressed quickly thanks to higher temperatures and gained ground on their early-season stresses, she said, although some “staginess” has been noted,
Producers may also get a break when it comes to sclerotinia this year, she added. Weather has not been favourable for the disease, which requires moisture for apothecia to germinate.
Soybeans also put on good growth after getting moisture, according to Froese.
“They’ve leapt about two to three growth stages in the last week and they’re largely just starting to flower,” he said.
The plants themselves, however, are short.
Both soybeans and canola also have more time before yield potential is locked in, something that may yet leave space for improvement if the province sees rain.
Heat risk fires up
Canola growers however, have another source of weather-related anxiety.
While heat in late June helped jump-start growth, bolting and blooming also got off to a hot start, leading to concern over heat blast.
“That’s something that’s on the radar,” Cornelsen acknowledged. “Obviously there’s nothing you can do about that. It’s just something you make note of.”
With the exception of far-north Manitoba, all Prairie provinces were under heat advisories going into the first weekend of July. Daytime highs in Manitoba remained into the mid-30s several days in a row, while overnight lows failed to fall further than the late teens or low 20s.
Cornelsen said overnight lows below 15-16 C often help ease plant stress.
The same heat that threatened to blast canola, however, had much of central Manitoba and parts of the southwest in the higher ranges of corn heat units, as measured by Manitoba Agriculture and Resource Development.
But while heat is a typical sign that corn is about to take off, Froese also cautioned that, “heat is only good if you have moisture to accompany it and help the plant cool down.”
If there is not enough water to move through the plant for transpiration, plants suffer “disproportionately” from excess heat, he said.
The saving grace that producers got in June — for those who did get rain — may yet turn into more of a stay of execution if the tap turns off, Burnett also noted.
“It’s almost the story of this year… we get a rain and then we say, ‘when is the next one coming?’” he said.
Burnett noted that June — now past — historically sees the growing season’s heaviest rain. Many crops were going to need another shot of moisture after the province’s heat wave moves through, he said.
Burnett is also looking south to North Dakota, typically around two weeks ahead of farms in Manitoba, as a forecast of this side of the border if more rain doesn’t fall.
“What we see is a very significant deterioration in the Northern Plain states over the last two weeks,” he said. “I think that is something that we are probably going to be looking at here, again, unless we get some really consistent rainfall within the next little while.”