How to Assess Wheat Fields for Frost Injury

May 11, 2020

Dennis Pennington

In this video, you'll learn how to assess winter wheat for frost injury.

Video Transcript

hi Dennis Pennington Michigan State

University wheat extension specialist

out in the field here today to talk to

you about how to assess winter wheat for

frost injury okay so when it comes to

staging the weed you want to pull out an

individual plant and this particular

plant has one main stem and it's got one

two and a third tiller starting to come

here right there staged your main stem

so don't try to stage the tillers so I'm

just gonna break these off here to get

down to here now what you're looking for

what you're trying to feel for is these

bumps or a node in in the stem so just

run your your thumb and your forefinger

up the stem and you can feel a bump and

when I do that I can feel one right here

and then I feel a second one up here but

I don't feel a third one yes so I have

two nodes which means if I had just one

it would be feet 6 to nodes means we're

at feet 7 and where the head is

developing head is that and the stem is

up here at the top of the upper most

known so we're gonna want to dissect

this to identify and find where that is

at where the developing head is and

we're just going to kind of finish our

staging discussion here so we're gonna

strip these leaves back what I'm looking

for is the leaf that is attached to this

bottom knowing because that will be

considered leaf number one and then

there'll be four leaves above it the

fourth leaf above it will be the flag

leaf which is the penultimate leaf which

is the last leaf out before the head

emerges so if I strip this back this

leaf right here is attached to this note

so this is leaf one this is leaf number

two this is leaf number three and then

right there is your flag leaf just

starting to emerge out of the world

right here so when we're staging this

trying to identify damage for frost we

want to slice this open so that we could

expose the head so I'm gonna slice this

open on my leg here and then I'll

explain what we're seeing inside the

plant or inside the stem

okay so I'll hold this stem open here

and down here at the bottom is our first

node right here and then there's what

this is what's called the space in

between these two nodes right here is

called our inner node space so this is

node number two this is what determines

that this one is at x8 Earth's sorry

feet seven and then the developing head

is actually pushed up right here and you

can see the little teeny tiny spikelets

on that head this is what we got to make

sure this remains viable after we have a

freeze event typically in Michigan we

don't have freeze events after the

growing point or the head is this far

above the soil surface usually once we

get to where the head is just above the

soil surface we're usually at the end of

our frost period so what we're looking

for is where this is the plant is and on

this particular one if I have lay this

down in my hand the head is probably

about four inches above the soil surface

at this point so what's going to be

critical I'm diagnosing this one is how

cold does it get and does it get down

below freezing and does this head freeze

being that it's four inches above the

soil surface so we'll have to wait for

probably four to seven days after the

freeze event to come back and assess is

this head okay or not so in terms of

assessing your field for freeze damage

the bottom line is you've got to know

how cold it's gonna get and enough for

how long is it cold and then you need to

stage your wheat and identify where the

growing point is where is that

developing head and how close is the

soil surface to really know how much

risk you have for a potential damage we

identified this growth stage of wheat in

this field it's at peak seven and that

developing head is about four inches

above the soil surface

so if we have killing frost down to

about four inches of height we could

potentially have some damage out here

and and we in this particular field is

at risk of having some frost injury so

we'll have to come back in about five to

seven days to really identify what the

kind of damage we had we can't determine

just yet but we will follow through with

that and follow up with with another

video if we have additional damage to

assess

MSU Extension Wheat