Lowering the water content reduces the probability of ice crystal formation within the plant cell. When ice crystals form, cell walls can be broken and death of the plant tissue results. Much of the carbohydrate in a plant root is starch. An untimely fall harvest will result in the utilization of starch for regrowth rather than conversion to sugar. Thus, the likelihood of winterkill increases.
Proteins also accumulate in the root during the fall period.