Extremely cold temperatures were experienced throughout Manitoba at the end of December and beginning of January. The cold temperatures combined with limited amounts of snow cover have many winter wheat producers thinking about winter survival.
Manitoba Agriculture’s Ag Weather Program has been monitoring soil temperatures in winter wheat fields for a number of years. There are currently three weather stations measuring real time soil temperatures in winter wheat fields at Alexander, Dauphin, and Kleefeld. The data collected from the weather stations is made available to the University of Saskatchewan and Western Ag Labs for their Winter Cereal Survival Model, available at: https://www.wheatworkers.ca/wcsm.php. The Winter Cereal Survival Model compares the cold tolerance of winter wheat varieties to the daily average soil temperature at crown depth (about 1”).
Plotting the soil temperatures against hardiness curves can give an early indication if there is a concern for winter injury or winterkill. Factors that can impact the level of cold hardiness of the plant include weather, fertility, seeding date, and seeding depth. In Manitoba, the majority of winter wheat acres would likely be considered to be well-hardened. The figure below shows soil temperatures at 1” depth in three winter wheat fields in Manitoba, plotted against three hardiness curves.
Figure 1. 2017/18 soil temperatures (as of January 16, 2018) measured at 1” depth in three winter wheat fields. Data Source: Manitoba Agriculture Ag Weather Program
Soil temperatures in Alexander and Dauphin dipped below the low hardiness curve, but have not approached the mid and high-hardiness curves at this point. To assess the level of risk on your farm consider how well-hardened your field may be and check your fields for level of snow accumulation. It is still early in the season, so check back in on the Winter Wheat Survival Model throughout the winter to get an idea of the risk of winterkill in your area.
Submitted by: Anne Kirk, Provincial Cereal Crops Specialist, Manitoba Agriculture