The weather has certainly been taking Kansans on a rollercoaster ride over the last several weeks. Temperatures have ranged from the upper 80s to the low 20s here and even lower in other parts of the state. The area has seen snow and rain with periods of dead calm and howling winds. Concerns have arisen regarding possible damage to the wheat crop with the cold temperatures. Wheat farmers would love for the markets to react to potential damage to the 2016 crop with increasing prices for the crop with no actual damage. There are two questions to answer. Why are producers concerned and was there any real damage?
• Before green up in late winter/early spring wheat should be dormant and tolerant of cold conditions – winterhardy. As days lengthen and temperatures warm it loses this winterhardiness and while it can regain some level of cold tolerance, it will be more susceptible. Over winter and until jointing, the growing point from which the head will develop is underground in a more protected environment and is protected the wheat canopy.
• After green up the plant moves from prostrate growth to erect growth on the main and the tillers. Jointing, the development of the first elevated node occurs. A leaf emerges from the node. The stem growth at the base of the plant turns from a solid to a hollow stem. The head starts to develop and rise above the soil surface. This developing reproductive tissue is sensitive to cold damage. Also the vascular system of the stem transporting water and nutrients up from the roots and sugars from the leaf to the rest of the plant can be damaged or destroyed.
• The amount of damage depends not only on how cold temperatures become but also for how long and the growth stage of the plant and the elevation of the developing head above the soil surface. Temperatures were cold enough and long enough to damage the crop. The question is what growth stage was the wheat crop at and what was the temperature were the wheat head was located?
• Temperature – temperatures vary across areas based on a number of factors such as topography. And the recorded temperatures are at 1.5 m above the ground (about 5 feet). The temperature at the surface is typically a bit warmer. And if the head is close to the soil surface, except under no-till with heavy residue, the soil radiates heat to help protect the soil. Also a good vigorous canopy will help insulate the developing head.
• Now producers wait. If the wheat hadn’t jointed it should be fine. If the main stem had jointed, it may have been damaged. However, other tillers that hadn’t jointed will likely be fine and some tillers that may have not produced a head will go ahead and produce a viable head. Wheat severely damaged may exhibit an off green color and under higher temperatures and wind look water stressed. If a damaged wheat stem is split open, the head will appear water soaked and limp. However, sometimes the damage will not exhibit itself until later as the wheat will continue to and the vascular tissue can’t provide an adequate supply of water and nutrients.
• We are still approximately a month or so away from the frost free date so producers will be keeping one eye on the weather and one on the wheat. Producers have always said wheat has nine lives and there are still several left.