Winter wheat agronomists with Ducks Unlimited are urging producers to be patient when assessing their crops and avoid making premature decisions about crop viability and abandonment.
In an April 4 webinar, Ducks Unlimited agronomist Janine Paly said growers should take their time and avoid making definitive assessments until mid-way through spring seeding at the earliest.
Essentially, growers who are worried about winter survival should give themselves ample time to make accurate assessments.
“The first thing I can tell you is … to be patient,” said Paly.
“Step back and don’t look at that field.… Walk away (now, but) monitor that field during spring seeding.”
Fields that aren’t showing signs of spring growth half way through seeding should be examined more closely.
Growers can use a couple methods to assess whether plants have survived winter.
Start by digging up plant samples from different parts of the field, including low lying areas, hilltops and areas that had varying levels of snow cover.
After collecting a good representative sample of what’s in the field, look for new root growth on the plants.
If there is no new root growth, peel back the stem tissue and look for white material.
The presence of white stem material means the plant is alive but needs more time to recover.
Growers who are still unsure can take their representative plant samples home, rinse the plants to remove any soil, place the plants in a moist paper towel and place the paper towel in a sunny area, ensuring that the towel is kept moist at all times.
If the plants are alive, new root growth should be evident within a few days. If the plants did not survive, the root material will quickly turn brown.
Paly also pointed to an online winter wheat survival model that growers can use to determine the level of winterkill risk in different parts of the Prairies.
To use the model, go to www.wheatworkers.ca/wcsm.php and select the variety of winter wheat that was seeded.
Then go to the map in the left corner of the screen and click on the pin that is closest to your growing area.
This will produce a pair of lines on the right hand side of the screen.
Points where the two lines intersect denote a heightened risk of winterkill, displayed in red.
The model uses probes to assess soil temperatures throughout the winter.
Paly said there are a variety of factors that can affect winter survival.
They include plant staging in the fall, snow cover, the date that significant snow cover arrives, the variety of winter wheat planted and the use of seed treatments.
Ideally, winter wheat crops will be in the three-leaf stage going into winter. This staging will ensure that carbohydrate levels are adequate to maintain the plants during the winter.
As winter progresses, carbohydrates are gradually drawn down.
Because of this, survival rates may be lower in areas that experience a prolonged winter period and extreme cold temperatures.
“Ideally you want to see that field in the three leaf stage,” Paly said.
“At the three-leaf plant stage, that plant in the fall should have had enough time to build up its carbohydrates.”
Factors linked to fall plant staging include seeding date, seeding depth and soil moisture conditions.
“If you were less than the three leaf stage — so the one or two leaf stage — that will have a higher risk of winter damage,” she said.
“That will be the first measurement of (the crop’s) ability to handle … stress.”
Crops that reach the three-leaf stage in the fall are least likely to experience any loss of yield potential because of winter stress.
Winter wheat crops generally require eight to 10 weeks of fall growth to ensure that they are completely hardened off and have achieved optimal winter survivability, Paly added.
Varietal selection is also an important consideration.
In addition to yield potential and other important agronomic characteristics, growers should consider the winter survival rating when choosing a variety.
Ratings vary from fair (F) on varieties such as Flourish and AAC Gateway to very good (VG) on varieties such as Radiant, CDC Buteo, AAC Wildfire, AAC Goldrush and Pintail.
AAC Elevate, Moats and Emerson are rated as good (G).
Paly said most winter wheat crops that were observed last fall in northern Saskatchewan and central to northern Alberta were in good shape entering the winter.
In those areas, “the majority of the fields that we saw (were) in the three leaf … (to) five leaf stage,” Paly said.
“So they’re well developed, and in most cases, they will have a high competitive factor against any kind of weeds. Their survival index will be at the peak … and the days to maturity should be right on par” with the variety’s maturity rating.
By comparison, crops that went into the winter in the one to two leaf stage could require an additional four days or so to reach maturity.
Winter wheat crops that were germinated but not yet emerged before the arrival of winter can still produce a crop, but yield potential and competitiveness is more likely to be compromised, the winter survival index is lower and days to maturity could be eight days or more above the variety’s rating.
Abandonment decisions should not be made before midway into the spring seeding season.
“That will give enough time for that (crop) to recover … and there is still enough time for you to make a decision … and put a Plan B in place,” Paly said.
Ideally, growers will see 20 to 30 plants per sq. foot during their spring assessments, but research has shown that plant densities as low as 10 plants per sq/ foot can still produce adequate yields.