Fall alfalfa management

As fall approaches and temperatures decrease, it’s important to decide whether that last late cutting is really worth it. I like to bring this up each year to remind growers about the trade-offs that come with late alfalfa cuttings.

Alfalfa requires about 500 uninterrupted growing degree-days to winterize- this translates to roughly six weeks (depending on temperatures). Alfalfa winterization typically begins about three weeks prior to the average date of the first 32°F frost. In South Dakota, this usually means late September to early October (go here for frost dates in your area).

Alfalfa plants determine winterization based upon day length and cooling average daily temperatures, hence the first average frost guideline. Plants cut during the winterization period will attempt to put on regrowth; this takes away from their ability to accumulate root proteins and carbohydrates, which may cause poor stand and vigor the following spring (think of a bear preparing for hibernation). It’s important to weigh the odds of an additional cutting against potential stand losses.

To avoid winter injury next spring, it is best practice to leave the alfalfa in the field at this point per the frost date in most of South Dakota. However, if you had late cuttings this year (as many did) and are in need of feed there are a few things to consider:

• For those looking to cut late in an effort to extend a high quality forage crop, cutting during winterization is a risk to weigh. The more stress an alfalfa stand sees during the growing season (ie: drought, insect pressure, disease, etc.), the more apt it is to experience winter-kill after a late cutting. If a field was cut multiple times (4+), it is more likely to have winter-kill issues than those that were cut fewer times. Younger standing, well-established, winter hardy/disease-resistant varieties may tolerate a late season cutting better than older stands or those that experienced heavy pest pressure over the growing season. Well-drained soils, adequate soil fertility, and insulating snow covers are also helpful in the way of avoiding alfalfa winter-kill. If the need for feed and price of hay outweigh the risk of stand loss next year, a late season cutting may be a risk you’re willing to take.
• Another consideration is harvesting after the winterization period; technically, it should be safe to take a cutting after winterization. This correlates to cutting after a killing freeze (23-24°F for several hours) after the plant is dormant. This is not as stressful to the plants as cutting during winterization, and can be a viable option for those who need feed and do not want to risk next year’s stand. However, remember that you should leave 5-6” of stubble, which leaves some plant tissue and helps to reduce erosion. Leaving soils bare over winter is a recipe for erosion and will likely result in less snow cover with little plant residue on the soil surface.

Alfalfa stands may last several years in various parts of South Dakota. Taking care of stands and skipping late fall cuttings can help prolong plant vigor and overall stand for years to come; however, challenging years (like this one in many parts of SD) may have created forage shortages and require producers to make tough decisions. For more information on alfalfa see the forage page on our website.

Winter wheat variety and forage trial results

The SDSU Crop Performance Testing program released the most recent winter wheat variety trial results recently. The crop performance testing program has been a popular, reliable, unbiased seed testing program in South Dakota for many years, turning over reliable data for public consumption.

This year, grain trials were held at Brookings, Faith, Hayes, Mount Vernon, Onida, Pierre, Platte, Selby, South Shore, Sturgis, Vivian, Winner, and Wall. Forage trials were conducted at Brookings and Pierre. Find a trial near you to aid in decision making for this year’s crop!

Please go here to see the results digitally at any time. Don’t see your favorite line or company represented? These trials are open, paid entry trials; it is up to each individual company/university to enter their varieties for testing. If you’d like to see more representation, contact your seed dealer about considering entry into these valuable trials!