NDSU Extension Service
North Dakota State University
Identifying Leaf Stages in Small Grain
W-564 (Revised), November 2007
Terry Gregoire,
Area Extension Specialist/Cropping Systems
Greg Endres, Area Extension Specialist/Cropping Systems
Richard Zollinger,
Extension Weed Specialist
Recommendations for postemergence applied
herbicides include leaf stages of crops and weeds to describe
the optimum treatment time. For example, achieving
maximum wild oat control with Avenge (difenzoquat)
or minimizing crop injury from Banvel/Clarity
(dicamba) requires proper timing of herbicide applications.
The drawings in this circular illustrate wheat growth stages
but also represent any cereal or annual grassy weed.
Weed control recommendations made annually by North
Dakota State University in Extension Circular W-253,
North Dakota Weed Control Guide, use this method of
describing growth stages. The numbering on the drawings
represents the following: 1=1st leaf on the main stem, 2=2nd leaf
on the main stem, (etc.), and T=tiller (not counted as
a leaf when determining leaf stages).
The plant leaf stage is determined by the number
of leaves present on the main stem. Leaves arise on
opposite sides of the stem and develop a collar at the junction of
the leaf sheath and the leaf blade. Small grains should
be positioned with the first leaf pointing to the left. The
first leaf has a blunt tip. When positioned correctly, all
leaves on the left side of the main stem are designated with
an odd number and on the right side with an even
number. Count the youngest leaf when it is at least one-half
the length of the leaf below it. For example, a plant with
two fully expanded leaves with the third leaf
approximately one-half the length of the second leaf is staged as a
3-leaf grass plant. Follow this procedure to determine the
proper growth stage of grass plants.
Tillers (stooling) usually start to appear at the third to fifth leaf stage. Most tillers arise between the main axis (stem) and leaf. A coleoptilar tiller may also be present. The coleoptilar tiller originates below the soil (near the seed) and is located on the opposite side of the stem from the first leaf. Frequently, tiller leaves are confused with the leaves of the main stem when determining the leaf stage. Remember to count the leaves on the main stem, but do not include tiller leaves in the leaf stage count.
Leaf stage determination in the field often is complicated by the loss of some of the older leaves; for example, the first and second leaves may have been removed from the plant by abrasion from wind blown soil, frost, disease, or some other form of weathering. The base of the stem should be carefully examined for evidence of scars from lower leaves which may have been removed. Such leaves must be counted when making a leaf stage determination.
Plant growth rates varies considerably, and the approximate days after emergence for a given leaf stage to
appear is influenced most by temperature. Daytime highs less
than 55 degrees Fahrenheit delay development, while
daytime highs greater than 75 F advance development. Days
to emerge can vary greatly depending on soil temperature
and moisture.
Approximate days or growing degree days after emergence for wheat growth stages. (Click here for a larger version of this graphic. 30KB)
Timing of postemergence herbicide application to hard red spring wheat, durum and barley. (Click here for a larger version of this graphic. 44KB)
This publication is also available in Adobe Acrobat format for better quality printing. 195KB
W-564 (Revised), November 2007
