Assessing Freeze Damage
Many alfalfa fields were damaged during last week's freeze. 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. This growing point, also called the apical meristem, is where all new leaves, stems, and branches initially develop on alfalfa. It is located inside the dense cluster of unfolded leaves at 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.
When the growing point is killed, however, growth ceases on that stem. Any new growth must come from new crown shoots or from lower branches. While the existing plant remains intact, re-growth often is delayed. But you don't have to harvest this damaged growth; plants will begin to grow again on their own although it might take a little longer. Cutting off damaged plants often hastens development of re-growth from good, healthy fields. But cutting also adds extra stress to the plants so you should wait until plants get a little more mature before you take your next cutting. I suggest cutting now only if there is enough growth to justify the time and expense of harvest.
Check your alfalfa plants to truly see if the tops and growing point are dead or if recovery has begun. Then decide whether to harvest or just wait for growth to renew naturally.