Assessing Freeze Damage to Alfalfa - UNL CropWatch, May 8, 2013

Assessing Freeze Damage to Alfalfa - UNL CropWatch, May 8, 2013

May 8, 2013

Frozen alfalfa usually needs time to recover before true damage estimates can be made. Now that we've had several warm days since last week's storm, it's time to recheck your alfalfa fields.

To assess the extent of the damage, don't just look for frozen or wilting leaves. You need to determine if the growing point was killed.

The growing point, also called the apical meristem, is the initial development source of all new leaves, stems, and branches on alfalfa. It is inside the dense cluster of unfolded leaves near the top of the main stem. Because it is inside a cluster of leaves, the growing point is somewhat protected from cold injury. Exposed leaves and stems all around it can be frozen, wilted, and dying while the growing point cluster survives, waiting for warm weather before continuing to grow. If the growing points in your
alfalfa survived the freeze, just wait for growth to begin again.

If the growing point was killed, however, growth ceases on that stem. New growth must come from new shoots at the crown or from lower branches. When a large existing plant remains intact, regrowth can be delayed, and harvesting damaged plants can hasten recovery.

This year, since most alfalfa fields don't have enough growth to justify harvest, I suggest just letting them come back on their own even if it takes a little longer.

Bruce Anderson
Extension Forage Specialist