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February 2014 Archives

Predicting the future: Alfalfa winter injury in Minnesota

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by M. Scott Wells

Over the past two and half months as the new U of MN Forage and Cropping System Extension Agronomist, the one question I have been asked the most is, "Are you surviving the winter?" Being from the southern US, I replied that I have now experienced real winter. Some of these experiences have been novel and interesting, such as tossing boiling water into the air and watching it become snow, and blowing bubbles in -15°F weather (if you not have tried the bubbles, I highly recommend it), whereas other experiences (truck not starting because its so cold) have been less thrilling.

This question about "surviving the winter" is an important one when considering the devastating impact of the 2012-2013 winter on alfalfa stands throughout Minnesota. If you are an Alfalfa producer, the question of alfalfa winter injury, and to a greater extent winterkill, is definitely on your mind as it is on mine.

Winter injury and winterkill of Alfalfa can be tricky to predict during an average winter where adequate snow cover (4 to 6 inches) persists throughout the season. However, this winter as been anything but "average" and with headlines such as: "Out of the blizzard, into the icebox; low temperature records may be shattered" (NBC News 1/4/2014); "Deep Freeze Recap: Coldest Temperatures of the Century for Some" (The Weather Channel 1/10/2014); "More frigid cold prompts Minnesota schools to cancel Thursday classes" (StarTribune 1/23/2014), and my personal favorite, "Minnesota weather remains frigid as heat wave hits Alaska" (KARE 11 News 1/28/2014); the question arises, how likely is winter injury and winterkill in Alfalfa this winter?

As mentioned above, severe cold temperatures measured at the alfalfa crown from 15 and 5°F and below can cause damage, and during prolonged exposure, kill the plant. Even if the plants are not killed, the full extent of the damage is not until the plants reach 6 inches of spring growth (early May).

Snow cover is essential in preventing soil temperatures from falling into the ranges where alfalfa is susceptible to winter injury and winterkill. Notice for both 2013 and 2014 how air temperatures dropped below the 5°F (e.g. bold black line, Figure 1), but what is more important than the air temperature is the temperature observed at the crown. In 2013 soil temperatures (e.g. 2-inches) were at or below 15°F (e.g. range for winter injury) for the months of January and February, and even worse, soil temperatures were measured below 5°F (Figure 1, black arrows). Even though the air temperatures were less severe than those experienced this year, the increased snow cover in 2014 has insulated the soil, preventing extreme changes in soil temperature, thus reducing the likelihood of alfalfa winter injury. Soil temperature at a 2 inch depth has mostly been above 20 F with periods where it reached near 16 F when air temperatures reached near-22°F. This illustrates the importance of managing alfalfa stands to increase snow cover retention.

Figure 1. Temperature and snow depth for Waseca Experiment Station during the winters of 2013 and 2014. *Critical temperature threshold for alfalfa winter injury and winterkill. **Minimum snow depth to buffer and insulate soil temperature from extreme air temperatures.

For the remainder of the winter and even into early spring, we need to watch out for alternative freeze and thaw cycles. These cycles can adversely affect alfalfa in several ways. (i) As the snow melts and refreezes, ice sheets can form. These ice sheets reduce the insulation factor of the remaining snow, thereby lowering the soil temperature at the crown, and much like the freezer bags use to keep your meat from spoiling in the freezer, the ice sheet restrict the diffusion of oxygen to the roots. The lower diffusion rates of oxygen to the roots, combined with the increased levels of carbon dioxide respiring from the roots, creates an anoxic zone (think low oxygen). (ii) The freeze-thaw cycles of the soil can physically lift alfalfa plants out of the soil via heaving. The heaved alfalfa crown is increasingly exposed to the elements and is more susceptible to winter injury. In extreme cases, alfalfa lateral roots can become severed, reducing the winter survivability and spring productivity. Typically heaving is more of an issue in wet, saturated soils, and less of an issue in well drained soils. (iii) Temperatures above 40°F can cause alfalfa buds to break dormancy. Once dormancy is broken, buds are much more susceptible to freezing damage. Plants with dead buds grow unevenly and slowly in the spring.

We cannot control the weather, or predict how severe the winter will be, as production decisions are made the prior year. However, we do possess tools to help decrease the incidences of winter injury, and many of these tools and management strategies are placed in motion long before the winter. These controllable management strategies include:

  • Selecting varieties with greater winter hardiness and disease resistance. For detailed descriptions of variety, disease resistance, and winter hardiness, see Minnesota Variety Trial Results 2012.
  • Managing younger stands. Stand age is important since older stands are more exposed to cumulative stressors of plant diseases and physical injury than younger stands, resulting in reduced winter survivability in the older stands.
  • Soil K Level. Soil potassium (potash) is very important in enhancing alfalfa tolerance to winter injury. Management of soil nutrients Phosphorus, Boron, and Sulfur along with pH (<6.5) is critical to ensure winter survivability.
  • Soil drainage is important from both a disease management and ice sheeting point of view.
  • Harvest management combined with the above management strategies provide producers with increased control over winter survivability. More frequent cutting will normally cause more plant stress (reduction in root reserves).
    • In general, three cuts are less risky than four-cuts in southern Minnesota. The last harvest in the three-cut system must occur before September 1st. By doing so, the Alfalfa has enough time to regrow and accumulate carbohydrate reserves in concert with undergoing the normal fall dormancy changes.
    • When considering four-cut systems, delaying the last cut until October 15th instead of September 15th, can reduce the likelihood of winter injury since there is minimal chance of reducing root reserves through fall regrowth.
  • Stubble height management from un-harvested plant residue insulates the soil, catches snow for insulation, and by shading the soil surface from sunlight can minimize freezing and thawing cycles.
Given the complex interactions, both climate-related and cultural, it is difficult to assess the degree of winter injury in Alfalfa. However, with the amount of snow-cover throughout the state, currently I think the risk for winterkill is minimal, but only time will tell.

by David Nicolai, Extension Educator-Crops

To help address key management issues of Northwestern and West Central Minnesota producers, Barriers to Bushels will be held at five locations in late February and early March. This is a program developed by University of Minnesota Extension aimed at current issues and research in corn/soybean crop production with the intent to ultimately help increase a producer's margins. Topics include: Managing Cost of Production (Bret Oelke), Key Soybean and Corn Diseases (Dr. Dean Malvick), Managing Inputs for High Yields While Controlling Costs in Corn Production (Dr. Jeff Coulter), Managing Herbicide Resistant Weeds (Dr. Jeff Gunsolus), Management Strategies for Avoiding SCN Pitfalls (Dr. Phil Glogoza), Optimizing Pop-up and Starter Fertilizers in Corn (Dr. Dan Kaiser), Insect Management Philosophy (Bruce Potter), and High Cost Management and Return in Soybeans (Dr. Seth Naeve).

Program Announcement: 2014 Southern Wheat Tour

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With increasing spring and fall workloads and problematic pests problems, including herbicide resistant weeds, wheat offers opportunities to diversity the cropping systems in southern Minnesota and manage these challenges cost effectively. The first objective of this program is to help farmers determine if wheat will work on their farm, in their rotation, and if it can be profitable. The second objective is to hand farmers the tools needed to make wheat a successful crop on their operation. This includes information on production agronomics, variety selection, disease identification and fungicide use, fertility, quality, and economics. Time will be set aside for open forum to discuss related topics and on farm experiences.

Dates, Locations, Times and Contacts are as follows:
February 25 - Slayton, Pizza Ranch, 1:00 - 4:00 (Contact: Liz Stahl at 507-372-3900 or Mike Boersma at 507-825-6715).

March 5 - Benson, McKinney's, 1:00 - 4:00 (Contact: Scott Lee at 320-760-6129 or Doug Holen at 320-589-1711)

March 6 - LeCenter, Fairground 4H Building, 12:30 - 4:00 (Contacts: Diane at 507-357-8230 or Doug Holen at 320-589-1711).

Presenters at all locations will include Jochum Wiersma, University of Minnesota Extension Small Grain Specialists, and Doug Holen, University of Minnesota Extension Small Grain Educator.

For more information or brochure contact Doug Holen.

Sauk Centre Hay Auction Summary Feb 6, 2014

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by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties by phone, if a local call to Foley 968-5077 or 1-800-964-4929

This information is for the Sauk Centre Hay Auction held on Feb 6, 2014.


This was a huge sale with 189 "loads" sold for tested hay and "bedding" materials.

Consider averages carefully... see further reading.

Information Links:

Feb 6 2014 SC Hay Auction.pdf  Individual lots sold, sorted and averaged by type and quality.

History of Selected Lots 2013-2014.pdf  A summary of past 4 years and individual auctions so far this year.  

Graph 2001 to 2014 SC Hay Auction.pdf   A line graph of for average from each sale 2001 to 2014 for Medium Square Alfalfa groups from 101 to 200 RFV. Where sale lots are limited, averages might not mean much.

Hay Stocks Dec 1 2013.pdf   This lists May 1 and December 1 Hay Inventory for the 48 states starting May 1, 2011. The % column is the % compared to the corresponding date the previous year. I also list the combined numbers for our 5 state area.

by David Nicolai, Coordinator for the Institute for Ag Professionals

The University of Minnesota Institute for Ag Professionals is holding an Ag Research Update on Thursday, Feb 13th which was re-scheduled due to a snow storm in January.  Another agronomy training opportunity is the Conservation Tillage Conference set for February 18-19 in St. Cloud. And finally the University of Minnesota is working with the Agricultural Fertilizer Research and Education Council (AFREC) to determine the need and opportunities for on-farm research in Minnesota. Your input is requested to determine if an on-farm research program should go ahead, and if so, what it should look like. The survey is described in this Crop-E news edition.

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