Everybody is talking about the lack of snow this winter, but like the weather, nobody can do much about it.
The fields here are bare and it’s the same for much of southern Manitoba. That’s raising concerns about possible winterkill to crops such as alfalfa, winter wheat and strawberries.
Snow is a good insulator. Fortunately there hasn’t been a lot of cold weather either. There was some before Christmas and a few cold days since, which potentially could’ve hurt some alfalfa stands, according to Glenn Friesen, forage specialist with Manitoba Agriculture, Food and Rural Initiatives (MAFRI). Much depends on the condition of the alfalfa when it went into winter, he said.
“We know that on average the alfalfa crown can withstand -12, which is one or two inches below the soil,” Friesen said in an interview Feb. 16.
Grass in alfalfa stands provides some insulation.
Four inches of “good snow” can keep the soil two inches below the surface 10 C warmer than the air temperature, Friesen said.
Strawberry growers routinely protect plants from the cold with a straw mulch.
MAFRI monitors soil temperatures at five cm at 33 places around the province. In the last two weeks temperatures have ranged from -4 to -12, said MAFRI cereal specialist Pam de Rocquigny. A -18, which is where winter wheat can be damaged, was recorded at one site, but it’s probably not representative of the field. Cracks in the soil might have allowed cold air to reach the sensor.
Winter wheat is hardiest in December and January — normally the coldest months of the winter, de Rocquigny said. As spring gets closer winter wheat’s cold tolerance declines. That tolerance also depends on how acclimated the winter wheat was going into winter. Cold tolerance also varies between varieties.
“I think we can probably safely say for plants that were well hardened going into the winter with three leaves and a tiller we haven’t hit the soil temperatures where we would be concerned,” de Rocquigny said in an interview Feb. 15. “But I know there were lots of acres that went in, in less-than-ideal conditions. The fall was dry. There were lots of concerns with germination. Obviously those plants wouldn’t be going into winter as well hardened as we’d like to see.”
This is Manitoba, so by the time you read this there could be two feet of snow on the ground. But if the snow doesn’t come and there’s a cold snap farmers should assess their alfalfa and winter wheat in early spring.
While dead plants can’t be resurrected, early assessment will give farmers more time to consider their options.
“It’s going to be a field-by-field assessment in terms of how the winter wheat fared and then making your management decisions from that point on,” de Rocquigny said.
If spring comes early farmers might be able to assess their winter wheat right in the field in April. Once weeds start to show signs of life dig up some crowns in search of new, white root shoots. Brown leaves mean nothing. The plant could be dead or alive.
To get an earlier start crowns can be dug up and taken indoors to see if they send out new roots.
“Often the plant stand is variable so deciding on keeping it is never an easy decision… for the producer,” de Rocquigny said. “It’s not black and white.”
The optimum winter wheat stand is 20 to 30 plants per square foot, but Agriculture and Agri-Food Canada research shows even eight plants per square foot can produce a 47-bushel-an-acre crop.
If winter wheat stands are thin farmers need to weigh the pros and cons of ripping it. If they reseed spring wheat they must ensure all the winter wheat has been destroyed. Living winter wheat could provide a “green bridge” resulting in the spring wheat being infected by wheat streak mosaic.
If a thin crop is left farmers should apply nitrogen early to help it along and control weeds earlier to because the crop will be less competitive, de Rocquigny said.
A stressed winter wheat crop could take longer to mature, making it more susceptible to fusarium head blight.
Alfalfa growers have similar decisions to make.
“If the plant is slow to emerge then it’s injured so you should be considering some remedial action or at least keeping an eye on it,” Friesen said. “Do your stem density counts and if you’re below the thresholds in the first part of the spring it’s your choice if you want to terminate it or take the first cut and then make a decision or add some fertilizer to bump up the yield as a band-aid solution. I don’t think this is the year guys want to stretch themselves thin on forage production.”
Excess moisture followed by dry weather last year resulted in a reduced forage harvest. Supplies are tight now and prices rising.
Pastures and forage crops aren’t soil tested as much as they should be, Friesen said.
“Water tends to change what the nutrient profile looks like… so if there was a time to do it, this is the time,” he said.
Manitoba’s strawberry fields are probably all right so far, if they’ve been covered with a straw mulch, Anthony Mintenko, MAFRI’s fruit crop specialist wrote recently on MAFRI’s website.
“We still need to be concerned with the potential occurrence of winter temperatures in the -25 to -30 C range for extended periods as the winter winds down in Manitoba in regions without snow cover,” he wrote. “Continue to monitor your strawberry fields and ensure that straw mulch is not being removed by wind or displaced by deer attempting to feed on dormant plants.”