The title of this short article may seem a paradox, but leave it to a Minnesota spring to create both problems within a few days from one another. On May 23, a severe night frost damaged many fields in northwest Minnesota. Fortunately, for spring wheat and barley the damage is cosmetic and will not require replanting. The reason for this is as simple as it is elegant. The tender growing point from which all leaves and eventually the spike is produced,  insulated and protected by the soil.  Approximately, the 5-leaf stage, the growing point is located at the crown at ± 1.5 inch below the soil surface. The crown is easy to recognize as a hard knob from which both roots as well as leaves start. This evolutionary adaptation to keep the growing point hidden and protected from the elements is precisely why small grains fit so well in this area. The damage to the emerged leaves is nicely described on page 13 of Section III in the Small Grains Field Guide. The affected leaves appear burned and have died back. New growth should not show any symptoms.

Within a few days the temperatures have soared into the nineties. This combined with high winds have exposed the young seedlings to a second abiotic stress. The heat at the soil surface has caused heat canker. The tender young tissue at the soil surface basically have been ‘cooked’ and this appears as a yellow band that is slightly constricted. As the leaf continues to grow, this yellow band (1/8 - 1/4") moves upward and away from the soil surface. If the hot and dry weather last for more than a day, repeated bands should become visible. A nice picture of heat canker is included on page 12 of Section III is in the Small Grains Field Guide.

Because of the high winds, the tips of leaves may break off at the yellow band and give a field a very ragged appearance. As with frost damage, damage from heat canker is temporary and should not affect further growth and development.