Agronomic Bulletin
Assessing Wheat Freeze Damage
March 2017
Recent cold temperatures across the US have
generated much concern and discussion about the
potential damaging effects to the wheat crop.
Careful evaluation can help determine the extent of
the damage. The growth stage of the wheat in your
area will be a key factor in determining the extent of
the damage. The severity and duration of the
freezing temperature are also important factors in
addition to the wheat growth stage.
Look closely at all tillers since they may not all be at
the same growth stage. Some stems (tillers) may
be jointed while others are not. What percent of the
stems are jointed at the time of the freeze? Stems
that are jointed will be more adversely affected by
the freeze than the stems that have not yet jointed.
It is important to wait at least one week after the
freeze to attempt to accurately evaluate the extent
of any freeze damage. Warmer temperatures are
needed so that healthy plants and tissue can
resume growth in contrast to damaged stems and
leaves that will wither and become necrotic.
For wheat that has not jointed, temperatures below
12 degrees Fahrenheit generally cause damage.
24 degrees Fahrenheit is the threshold for freeze
damage for wheat that is at the first jointing stage.
See tables below. For areas in the northern US,
wheat that is not close to jointing will likely have
cosmetic leaf burn and may have a very slight yield
reduction that is nearly impossible to measure.
Keep in mind that even though the wheat may have
broken dormancy and resumed growth, snow cover
may have insulated the wheat in areas that got
below 12 degrees. In other areas where wheat has
begun to joint, a hard freeze can kill the growing
point on jointed stems causing them to die and
produce no head. Splitting the stem a week or
more after the freeze will allow you to evaluate the
viability of the growing point much like you would do
with corn seedlings.
AGRONOMY BULLETIN
It is possible that primary tillers could be killed by a
freeze, but secondary tillers that have not jointed
might escape damage and produce a normal head
& yield. In areas where the wheat is further along in
growth stage, it is possible that a freeze could
cause portions of the head to be sterile and produce
no grain. In severe cases, the entire head may be
sterile and produce no grain.
One additional potential symptom of freeze damage
that is of concern is damage to the cells & tissue of
the stem near the joint (node). Should this occur, it
can be observed by looking closely for a brown or
discolored mark on the stem near the joint. More
severe cases may show some slight splitting of the
stem. Wheat with this type of damage will continue
to grow normally and can put on normal,
undamaged heads. However, during grain fill as the
heads begin to gain weight, the plants will lodge.
This prematurely ends grain fill and makes harvest
impossible, resulting in a complete crop loss. It is
typical to see this type of damage in low lying areas
of fields where the temperature may have been
slightly lower. This type of freeze damage often
catches farmers by surprise because the crop looks
quite normal long after the freeze damage occurs.
This type of freeze damage is often misdiagnosed
as natural lodging associated with inferior varieties.
The two can be distinguished prior to maturity when
there is still green color in the stem. Naturally
lodged plants will have green healthy tissue all the
way to the crown and usually attempt to “goose
neck” or stand back up, much like a corn plant that
had lodged but not snapped. Lodging from freeze
damage often has brown or bleached areas of the
stem that become broken or kinked, which causes
the lodging. These plants can look quite normal
with green leaves and most of the stem being green
except for the discolored areas of the stem that
were freeze damaged. Freeze damaged plants that
lodged do not attempt to “goose neck” or come back
up.
Page 1 of 4
DYNA-GRO AGRONOMY SERVICES
©Copyright 2017. This information may have been accumulated from publicly available sources outside of Dyna-Gro Seeds, or its affiliates. Individual results may vary, and performance
may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Dyna-Gro®
is a registered trademark of Loveland Products, Inc. Featured logos are service/trademarks of their respective owners.
Agronomic Bulletin
Weather in early 2017 looks like it could produce a
challenging year for wheat. Planting dates and
differences in maturities among varieties might
create unnatural differences in yield this year.
Fuller season varieties and/or varieties that were
planted later could have an advantage over others
that were subjected to more freeze damage.
Varieties also differ in their photoperiod sensitivity;
this will be particularly evident in years like this with
February temperatures well above normal.
Varieties with poor photoperiod sensitivity will break
dormancy and resume growth with warm
temperatures making them more subject to freeze
damage. Varieties with good photoperiod sensitivity
will wait to advance through the reproductive growth
stages until the proper day length has been
achieved, regardless of temperature. There are
numerous varieties on the market today that have
many wonderful attributes, but may have a bad year
in 2017 because they have poor photoperiod
sensitivity.
It will be difficult to accurately compare varietal
performance in 2017 because of differences in
photoperiod sensitivity, maturity, and planting date.
If freeze damage does cause separations in
performance this year, selecting only what did well
this time will cause us to plant too many full season
varieties next year. Shifting maturities based only
on this year’s performance could be a problem in a
year with a different type of weather pattern. Let’s
make sure we are making careful and accurate
comparisons when harvest data is available.
AGRONOMY BULLETIN
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DYNA-GRO AGRONOMY SERVICES
©Copyright 2017. This information may have been accumulated from publicly available sources outside of Dyna-Gro Seeds, or its affiliates. Individual results may vary, and performance
may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Dyna-Gro®
is a registered trademark of Loveland Products, Inc. Featured logos are service/trademarks of their respective owners.
Agronomic Bulletin
(graph adapted from A.W. Pauli)
AGRONOMY BULLETIN
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DYNA-GRO AGRONOMY SERVICES
©Copyright 2017. This information may have been accumulated from publicly available sources outside of Dyna-Gro Seeds, or its affiliates. Individual results may vary, and performance
may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Dyna-Gro®
is a registered trademark of Loveland Products, Inc. Featured logos are service/trademarks of their respective owners.
Agronomic Bulletin
Growth stage
Appx. injurious temp. (2 hrs.)
Primary symptoms
Yield effect
Tilering
12 F (-11 C)
Leaf chlorosis; burning of leaf tips; silage odor;
blue cast to fields
slight to moderate
Jointing
24 F (-4 C)
Death of growing point; leaf yellowing or
burning; lesions, splitting, or bending of lower
stem; odor
Moderate to severe
Boot
28 F (-2 C)
Floret sterility; spike trapped in boot; damage to
lower stem; leaf discoloration; odor
Moderate to severe
Heading
30 F (-1 C)
Floret sterility; white awns or white spikes;
damage to lower stem; leaf discoloration
Severe
Flowering
30 F (-1 C)
Floret sterility; white awns or white spikes;
damage to lower stem; leaf discoloration
Severe
Milk
28 F (-2 C)
White awns or white spikes; damage to lower
stem; leaf discoloration; shrunken, roughened,
or discolored kernels
Moderate to severe
Dough
28 F (-2 C)
Shriveled, discolored kernels; poor germination
slight to moderate
Chart from University of Missouri “Understanding Wheat Growth Stages for Estimating Wheat Freeze Injury” Published: March 9, 2017 by
Gregory A. Luce
AGRONOMY BULLETIN
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DYNA-GRO AGRONOMY SERVICES
©Copyright 2017. This information may have been accumulated from publicly available sources outside of Dyna-Gro Seeds, or its affiliates. Individual results may vary, and performance
may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Dyna-Gro®
is a registered trademark of Loveland Products, Inc. Featured logos are service/trademarks of their respective owners.