Assessing Freeze Damage to Alfalfa

May 31, 2022

By Bruce Anderson

Did your alfalfa suffer freeze or frost damage last weekend? Frozen alfalfa usually needs some time to recover before damage can be estimated.

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.

If the growing point was killed, however, growth will cease on that stem. Any new growth must come from new crown shoots or from lower branches. While the existing plant remains intact, regrowth 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 regrowth from good, healthy fields. But cutting also adds extra stress to the plants so if you do cut the damaged plants, before you take your next cutting, wait until plants get a little more mature. I suggest cutting now only if there is enough growth to justify the time and expense of harvest, which is unlikely for most fields.

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.

Source : unl.edu

Video: Spring 2026 weather outlook for Wisconsin; What an early-arriving El Niño could mean

Northeast Wisconsin is a small corner of the world, but our weather is still affected by what happens across the globe.

That includes in the equatorial Pacific, where changes between El Niño and La Niña play a role in the weather here -- and boy, have there been some abrupt changes as of late.

El Niño and La Niña are the two phases of what is collectively known as the El Niño Southern Oscillation, or ENSO for short. These are the swings back and forth from unusually warm to unusually cold sea surface temperatures in the Pacific Ocean along the equator.

Since this past September, we have been in a weak La Niña, which means water temperatures near the Eastern Pacific equator have been cooler than usual. That's where we're at right now.

Even last fall, the long-term outlook suggested a return to neutral conditions by spring and potentially El Niño conditions by summer.

But there are some signs this may be happening faster than usual, which could accelerate the onset of El Niño.

Over the last few weeks, unusually strong bursts of westerly winds farther west in the Pacific -- where sea surface temperatures are warmer than average -- have been observed. There is a chance that this could accelerate the warming of those eastern Pacific waters and potentially push us into El Niño sooner than usual.

If we do enter El Nino by spring -- which we'll define as the period of March, April and May -- there are some long-term correlations with our weather here in Northeast Wisconsin.

Looking at a map of anomalously warm weather, most of the upper Great Lakes doesn't show a strong correlation, but in general, the northern tiers of the United States do tend to lean to that direction.

The stronger correlation is with precipitation. El Niño conditions in spring have historically come with a higher risk of very dry weather over that time frame, so this will definitely be a transition we'll have to watch closely as we move out of winter.