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Get A Jump On Gauging Winterkill

Winter wheat gets growing again as soon as the snow recedes, assuming it made it through the winter OK. A prolonged fall across most of the Prairies created some tough harvesting conditions that may or may not have negatively affected winter wheat survival. With good snow cover, winter wheat can handle a quick trip into the deep freeze. It’s exposed crop or iced-over fields that you have to worry about. Of course, nature can surprise even the most seasoned grower — the only sure way to know how the crop made it through winter is to let it grow.

Evaluating fields in later March or early April is a good place to start, however, if temperatures stay very low re-growth can be sluggish, leaving you with very little time to reseed, if necessary. Martin Entz, professor at the University of Manitoba, suggests getting out there now and doing a little digging.

“Get out in the field as soon as the snow recedes and dig up a few representative plants. We have even chipped them out of the ice in early March,” he says, so there’s no time like the present. “Plant them in shallow pots and stick them on the windowsill,” Entz says. The extra warmth of the house will speed along growth and give you a much earlier indication of winterkill.

The key here is digging up plants that represent the field’s make up. Low spots are prone to icing over, and any area that struggled to establish in the fall is more likely to not make it through the winter.

You don’t need to dig down far — it’s the crown of the plant you want. Leaves and lower roots are not very winter hardy but are also not necessary for regrowth. What you want is the actual crown. Dig them up, place two or three plants in 3″ to 4″ pots, keep them well-watered and check back in about a week. Healthy plants will have started to send out crown roots within about seven to 10 days. “If you don’t see any crown roots by day 14, the plant is more than likely dead,” Entz says.

What exactly are you looking for? Entz says to look for crown roots that emerge at a 45 degree angle. You’ll likely see two roots — one from each side. They’re relatively thick.

WINTERKILL ASSESSMENT IN THE FIELD

If you miss the early window, here are some quick tips to assess winterkill in the field. These tips are from a factsheet on the Winter Cereals Canada website found at www.wintercerealscanada.org/survival1.pdf.Ducks Unlimited also has a winter wheat stand assessment factsheet at www.wintercereals.ca/docs/spass.pdf.

Assess the crop between May 15 and May 25. This gives the crop time to regrow, while also giving you time to reseed if necessary.

Look for new growth in the form of white roots arising from the crown tissue

Proper spring nitrogen management will be required to increase competitiveness of injured stands Additional herbicide and fungicide operations may be required

The factsheet notes that winter wheat has a greater capacity to rebound after adverse conditions and produce yields compared to a spring wheat crop of similar density. The optimum plant stand is 20 to 30 plants per square foot however half of these numbers will produce an adequate crop due to the ability of winter wheat to aqgressively tiller, according to the factsheet.

If you do choose to reseed the factsheet recommends:

Wheat streak mosaic may carry over from infected winter wheat into spring seeded cereals. Avoid replanting to cereals, especially wheat.

Tillage and/or burndown herbicides will not likely control all plants, particularly if some are suffering injury and slow spring growth. Delay applications until the plants have greened up and are actively growing. ln-crop volunteer cereal herbicides may be required.

Remember to credit any spring-applied nitrogen to the following crop.

Lyndsey Smith is editor of Grainews.

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