By Joanna Follings, OMAFRA Cereals Specialist
Co-written by Dave Hooker, University of Guelph, Ridgetown Campus
Winter wheat can often be found to survive short freeze thaw events throughout the winter. However with the recent dips in temperatures with little to no snow cover, there are some concerns about crop damage and survivability. There is also some concern that more cycles of day-night freeze-thaw cycles in 2018 may be causing more frost heaving and unthrifty or dead plants once growth resumes. Incidentally, most winterkill occurs in Ontario under ice or frost heaving, rather than cold temperatures.
The risk of cold damage after the crop has come out of dormancy may increase when temperatures at the crown are below -10°C. Although many nighttime temperatures have been cool, the temperatures at the crown have likely been warmer than -10°C in many regions over the past two weeks. In regions where temperatures have dipped below -10°C for more than 48 hours, there has been some snow cover providing insulation to the crop.
It is important to walk your fields and assess the crop after a week or two of warm weather (if it ever arrives!), particularly those fields that may be at higher risk of winterkill. These fields include: those that were planted shallow, had frost heave problems (planted too shallow!), planted with a variety that has poor winter hardiness, were planted late or had ponding throughout the winter.
When making winter wheat assessments for winter survival, fields should be walked in late April to early May after growth resumes, with the replant decision to another crop being made as late as possible. When evaluating wheat stands you need to count the number of plants per foot of row.
It is also important to assess the health of the plants themselves to determine whether plants are actually going to survive or not. Are the plants well anchored into the ground or is the seed lying on the soil surface with the plant holding on by a single root? If plants are not well anchored, do not include them in your stand counts as they are less likely to survive.
When making assessments do not focus on bad spots in the field. Conduct a number of stand counts and plant health assessments throughout the entire field to get a broader perspective of what is happening. If 5% of the field is in poor condition and the remainder of the field is in good condition, do not take the wheat out. Also, be sure to consider the planting date. If the wheat was planted early, it has more yield potential.
See full article at fieldcropnews.com.