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Frost Damage on Cereals

Joel Ransom

Extension Agronomist - Cereal Crops

May 21, 2003

With the exception of winter wheat, the growing points of emerged cereals are currently still below the surface of the soil and are well insulated from short periods of freezing temperatures. The growing points of spring wheat and barley remains below the soil surface until jointing starts, usually around the 5 to 6 leaf stage. Similarly, the growing point of corn remains below the soil surface until the 5 or 6 leaf stage. Earlier this week in parts of the state, the frost was quite severe. These low temperatures will no doubt cause some damage to the emerged leaves. When temperatures are cold enough (the temperature varies depending on the tissue, crop, and other environmental factors) the contents of cells freeze, causing small ice crystals to form and pierce through cell membranes. The allows the cell�s contents to leak resulting in cell death. Damaged leaf tissue first appears water soaked, and eventually turns brown. Usually within one or two days new leaves will start to emerge from the whorl. Slight damage to the leaves will have little or no effect on yield or plant development. Severe leaf damage may reduce yields slightly and delay the development of the plant. If you suspect that the plant has been killed (the growing point damaged) by the frost, you can cut the plant in half vertically and check the growing point. A healthy growing point will have a bright white to cream colored appearance. Darkening tissue or a watery appearance usually indicates that the growing point was damage and that it will soon die.

There can be large differences between small grain varieties to frost, but information on the currently produced spring wheat and barley cultivars is lacking. Research in growth chambers indicate that spring wheat tends to be more tolerant to frost than barley. When growth staging a frost damaged crop, you should continue counting leaves as though the plant had not been damaged. For example, if your barley plant has 3 leaves that were damaged by frost, the next leaf that emerges will be the 4^th leaf (not the first leaf). Generally a severe frost will only delay the normal development of the crop by a few days at most.

Winter wheat is just starting to joint throughout much of the state. This means that the growing point is no longer below the surface of the soil and is now susceptible to frost damage. The growing point is the most susceptible part of the plant to frost and can be injured even though the leaves show little signs of damage. Occasionally the main stem can be damage while the tillers survive, resulting in uneven maturity of the crop. Frost during the jointing stage of winter wheat can have a moderate to severe impact on yield.

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North Dakota State University
NDSU Extension Service