Managing winter-damaged wheat
Growers are faced with difficult decisions as winter has taken a toll on many winter wheat fields.
There is evidence of significant winter-kill within some Michigan wheat fields. The loss is primarily due to layers of ice and water that suffocated the wheat between January and March. Much of the sheeting probably occurred below layers of snow. In some cases, the persistent cold temperatures of winter may have compounded the damage.
Where ice-sheeting is the primary cause of damage, there is often no relationship between the extent of damage and the wheat’s date of planting or variety. While very coarse soil may have some advantage, the extent of subsurface drainage usually does not seem to matter. There is, however, a tendency for more damage on level-lying fields. This is particularly evident this spring in the Thumb region where rolling terrains may only have 5 to 10 percent damaged wheat whereas some fields with less than 4 percent slopes have sustained at least 50 percent loss.
The extent of damage, or yield potential, in a particular field is difficult to gage. Generally, when extensive damage from ice-sheeting occurs, the damage usually exhibits itself as an irregular patch-work of dead areas across the field as opposed to plant-thinning within the rows. This means that that the percent of the field exhibiting live plants may relate 1:1 to a revised yield estimate. So, for example, where 80 percent of a field appears to have healthy wheat, it may be reasonable to assume the field will ultimately attain 80 percent of its original yield potential. Granted, this estimate can be muddled by a marginal edge having both dead and live plants. In these fringe areas, the live plants will compensate to an extent, but some might also be injured to a degree that is difficult to quantify.
Where wheat has extensive damage, growers will need to decide how much to destroy to make way for another crop. This entails more guess work of course. One will need to weigh the costs and potential income of the injured wheat crop against that of a competing crop. A budget work sheet, the 2014 Crop Budget Simulation Template, is available from Michigan State University Extension farm management educator Dennis Stein. It is a useful tool for plugging in various potential yields to help determine a reasonable range of outcomes.
Going forward, growers are encouraged not to rush to apply fertilizer nitrogen if they are unsure of keeping a particular field of wheat. The value of the crop will be increasingly clear as each day passes and nitrogen can be delayed until jointing (approximately the first week of May in central Michigan) without significantly effecting yields.
In managing damaged fields, growers might do well to consider reducing input costs on those areas where the yield potential has been reduced. Nitrogen rates should be reduced to reflect the adjusted yield potential, approximately 1.1 pounds of nitrogen for every bushel of anticipated yield. Fungicides generally applied during the early to mid-vegetative stages might also be reduced or excluded if few early diseases develop. In most cases, a fungicide application of Caramba or Prosaro at early flowering is still advised. Also, growers should plan to use a herbicide as weeds are likely to be more of an issue in thin or weak wheat.