Estimated Yield Potential for Freeze Damaged Wheat
Carrie Knott, Extension Agronomist-Princeton, University of Kentucky
Now that there has been time to assess any damage that may have occurred after recent overnight temperatures were near or below 24°F, it is time to decide what to do with the wheat crop.
The first thing we all need to do is take a moment to realize that:
There is no reason for rash decisions; we have time to make wise management decisions!
The most important information is the number of viable plants that still remain in the field. This will help determine potential yield of the wheat crop.
Historical data from Kentucky suggest that the final stands of wheat would need to be about 40% or less to significantly impact final yield.
Table 1. Modified excerpt of Table 3.4. Wheat yield potential based on plants per square foot from Comprehensive Guide to Wheat Management in Kentucky including estimated tiller counts.
However, in a recent 2 year study (2017 and 2018) it was found that the yield potential can remain quite high even with very reduced numbers of plants (plus tillers) per square foot. This data is based upon determining number of stems (tillers and original plants) prior to Feekes 3, but it could provide some indication of potential yield loss following a freeze event.
In this study the percentage of final targeted plant stands were:
140% for 130 to 165 plants per ft2
125% for 120 to 129 plants per ft2
110% for 110 to 119 plants per ft2
100% for 100 to 109 plants per ft2
90% for 90 to 99 plants per ft2
80% for 80 to 89 plants per ft2
70% for 70 to 79 plants per ft2
60% for 60 to 69 plants per ft2
50% for 50 to 59 plants per ft2
40% for 40 to 49 plants per ft2
30% for 30 to 39 plants per ft2
20% for 20 to 29 plants per ft2
10% for 10 to 19 plants per ft2
1% for 1 to 9 plants per ft2
Therefore, wheat stands will likely need to be almost totally eliminated by a freeze event before significant yield impacts may be realized. We have seen this from past freeze events. What seemed to be very poor stands produced acceptable yields, considering the freeze damage that the wheat crop sustained.