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Predicting the future: Alfalfa winter injury in Minnesota

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by M. Scott Wells
mswells@umn.edu

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.

weatherfigf.jpg
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.

Corn Silage Trial Results Available

Larry D. Jacobson, Extension Agricultural Engineer, U of M Extension

With the harvest season fast approaching, the application of stored manure from animal facilities on the harvested fields will soon follow. This year, pork producers need to be aware of the risk of spreading Porcine Epidemic Diarrhea (PED) through equipment used to pump and land apply manure from all farms but especially those with pigs exhibiting clinical signs of the disease. PED can be spread through oral-fecal contact, manure contaminated boots, clothing, birds and wildlife, transport trailers and other equipment.

PED is a viral enteric swine ONLY disease with clinical symptoms of diarrhea, fever, vomiting, and death (age dependent). PED was first detected in the United States this spring and as of the first of September the disease had been confirmed on more than 500 swine herds in the United States. Spread of the virus continues, and it is both a good animal husbandry practice and a good neighbor policy for all pork farmers with pigs exhibiting clinical signs of PED to obtain a confirmed diagnosis and immediately establish enhanced biosecurity practices to avoid spreading the virus within their own animals and (or) to neighboring swine herds.

Because many pork producers hire commercial manure applicators to pump and land apply their manure from a farm's storage pits, tanks, and/or basins, their equipment can easily spread this virus from infected farms (barns) to uninfected farms (barns). In response to this urgent concern, the National Pork Board (NPB) along with several midwestern universities (Michigan State, Iowa State, and Minnesota) have just released a one page fact sheet listing the biosecurity recommendations that commercial manure haulers should follow to reduce the risk of spreading this virus.

The fact sheet emphasizes the need for the manure applicator to communicate closely with the pork producers when pumping manure on a farm to reduce the risk of transferring this virus by manure handling equipment either from or to the farm.

The fact sheet is available here: NPB's PED biosecurity recommendations for manure pumpers, 9-6-13.pdf

Weed Management in Prevented Planting Acres

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By Jeffrey L. Gunsolus, Extension Agronomist - Weed Science

The wet weather pattern this spring and early summer has left a significant number of acres, especially in southeastern MN, unplanted.  Current estimates in southeastern MN project 30% of the tillable acres have not been planted and on many of these acres weeds such as giant ragweed, common lambsquarters and waterhemp are thriving. 

Although weeds are beneficial from an erosion control perspective their rapid growth will make seedbed preparation for planting cover crops very difficult and weed seed production potential will challenge even the best weed management tactics available in 2014.

By Lizabeth Stahl and Jill Sackett, Extension Educators

 

The challenging spring of 2013 resulted in wide-spread planting delays across the state and a significant amount of acres that remain unplanted at this time.  If the decision has been made to take the "prevented planting" option for insurance purposes, the question remains about what to do with these acres.  Leaving the ground bare greatly increases the risk of not only soil erosion, but also the risk of "Fallow Syndrome" the following year. 

Late Planted Forage Crop Options

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by Dan Martens, Stearns-Benton-Morrison Counties
Some farmers have been still trying to plant corn for silage or other forage crops to meet feed needs for dairy and beef cattle. Recent rain has made a mess of these efforts again recently.
One of the more recent field trials done to look at Late planted forage crop options was done in Pelican Rapids and Rosemount in 2002 and 2003. I am posting a report of that study here.

Late planted forage trial 02 03.pdf

University of Wisconsin Extension has also dealt with this issue over the years. You might find some additional useful information at

http://www.uwex.edu/ces/forage/articles.htm





Snow, rain, mud, now what?

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crop news late plant  pic 4.jpg

The weather has put us in a bind. Significant amounts of planting have yet to be completed, which has led to questions on the "correct" course of action. There will be no one "correct" course of action and with fields unsuitable for planting and more rain in the forecast there will be no easy decisions. One choice could be to utilize prevented planting, a choice that is appropriate for some and will lead to many other decisions to be made. A second option is to switch corn acres to soybeans; this may also be a wise and appropriate decision for some acres. Remember when planting soybeans after June 10th it is generally recommended to drop 0.5 RM from your typical full season varieties. The final choice is to stay the course and plant corn, a perfectly viable option for some acres.
A full set of delayed planting resources can be found at: http://z.umn.edu/lateplanting

By David Nicolai and Doug Holen, Extension Educators - Crops


The University of Minnesota Extension Forage Team has developed a list of resources available to livestock and alfalfa producers affected by the recent alfalfa winter injury and winterkill in 2013. These resources are available at the U of MN Extension crops website http://www1.extension.umn.edu/agriculture/crops/spring-issues/

By Dr. Craig Sheaffer, David Nicolai and Doug Holen

An unusual amount of winter injury and winterkill of alfalfa stands occurred in south central and southern Minnesota. While reports do not represent a detailed analysis of where injury to alfalfa has occurred across Minnesota, they do suggest a need for producers to check on stands and evaluate them for potential winter injury.


Les Everett - Water Resources Center Education Coordinator, U of M. Randy Pepin and Jose A. Hernandez - Extension Educators, University of Minnesota - Extension

Using grid soil sampling to guide manure application can be a profitable investment, is the conclusion from case studies based on eight Minnesota farms. In fields where there is a history of non-uniform manure application, targeting new manure applications to areas with lower phosphorus and potassium soil test values can result in considerable economic returns above the cost of grid soil sampling. Variable rate manure applicators are not required when fields can be divided into application and no-application zones, with supplemental nitrogen fertilizer in the no-manure zones. The brief case studies are available on the University of Minnesota Extension web page for Manure Management and Air Quality http://www.manure.umn.edu, under Grid Soil Sampling for Manure Application. An introduction, the eight case studies, and a set of short video presentations based on the case studies are available at http://z.umn.edu/gridsoilsampling.

Funding for the development of these case studies was provided by the McKnight Foundation.

By Daniel Kaiser

University Extension Soil Fertility Specialist

With the extreme variability in growing conditions there have been some questions regarding the variability in soil test. A project is being launched to establish a series of sentinel plots to study the monthly variation in soil test values over the next two growing season. We are looking for participants that are willing to take samples from a single point within a field and mail them off to us at Saint Paul. The goal of this study is to gain a better understanding of what is happening over the growing season for a number of different nutrients commonly measured.

University of Minnesota Extension is presenting workshops for livestock producers and ag professionals on the use of grid soil sampling to guide manure application. Grid soil phosphorus and potassium maps from Minnesota livestock farms are used to create manure application zones and manure exclusion zones within fields in order to maximize the economic value of the manure as a fertilizer replacement and minimize phosphorus in runoff. Determination of manure application rates and supplemental fertilizer where necessary are part of the demonstration and discussion. Eight case studies are posted on the UM Extension manure website, http://z.umn.edu/manure .

Since the number of workshops funded by the McKnight Foundation project grant is limited, we invite county feedlot officerss and NRCS/SWCD staff to attend one of the following workshops. The workshop presentation Powerpoint is available for those wishing to conduct their own workshops, and a few more workshops could be presented by Randy Pepin, UM Extension (pepin019@umn.edu).

Workshops have been held Feb. 12, 26, and 27. Remaining workshops and hosts are:.

March 5: 11 a.m., Lake Crystal American Legion, Diane DeWitt, UM Extension.
March 6: 1 p.m., Murray County Courthouse, Slayton, Mike Boersma, UM Extension.

U of MN Field Crop Trials Bulletin Available

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By Lizabeth Stahl

The University of MN Field Crop Trials Bulletin is now available in print and electronic forms. The new publication, dated January 2013, provides results from U of MN trials conducted in 2012 across the state. The varieties tested are from both public and private breeding programs and include U of MN developed forage, grain, and oilseed crop varieties.

Using Drought-Stressed Corn for Forage

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By Lizabeth Stahl, Extension Educator - Crops

Drought conditions continue to intensify in areas across the state including Southwestern Minnesota.  According to the July 24, 2012, U.S. Drought Monitor report, the southwest corner of the state is now rated in the "Severe" drought category.  The western half and southern counties of the state are also rated as "Abnormally Dry" or in the "Moderate" to "Severe" drought categories, and throughout this area soil moisture levels are low.  For example at the U of MN Southwest Research and Outreach Center in Lamberton, soil moisture levels are less than half the historic average for this time of year, and what moisture remains is almost all at a depth of more than 3 feet.  In areas hardest hit by the drought, growers are assessing grain yield potential and if or when to harvest drought-stressed corn for forage. 

By Daniel Kaiser
Extension Nutrient Management Specialist

The dry conditions in March and April have given way to extremely wet areas in some parts of Minnesota.  Since alfalfa stands got an early start this year there were a few concerns popping up early in the southeastern part of the state on areas of fields yellowing.  While there may have been some effects due to the cool weather in April a couple of nutrient could be of concern.

By Jennifer Obst, Minnesota Agricultural Experiment Station, 612-625-4741

A comprehensive comparison of most crop varieties grown in Minnesota is now available in print and electronic forms. Minnesota Varietal Trials 2012, published by the Minnesota Agricultural Experiment Station, provides the results of the 2011 University of Minnesota evaluation of more than 1000 individual entries of plant varieties.

2011 Corn Grain and Silage Hybrid Trial Results Available

 

By Daniel Kaiser
Extension Soil Fertility Specialist

U of M Nutrient Management Website

A new nutrient management website has been launched that houses most of the current fertilizer suggestions and data from the University of Minnesota. This website was made possible by funding from the Minnesota Agricultural Fertilizer Research and Education Council and was put together through a joint effort for several researchers from the University of Minnesota who's research focuses on nutrient management issues for several crops growth throughout the state of Minnesota.  We would like to thank the AFREC program because without them this effort would not have been possible

Can't-Miss FORAGE Gathering in St. Cloud Nov. 16-18!

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Plan Now for Successful Corn after Alfalfa

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Authors: Dimitre Mollov and Jennifer Flynn

When crops or plants are not growing well and look diseased or less vigorous than healthy plants, an accurate diagnosis of the problem may be critical to reducing and managing it. The Plant Disease Clinic at the University of Minnesota in St. Paul is open year-round to diagnose crop and plant problems and to assist with other plant testing questions. The Plant Disease Clinic welcomes samples from anyone and offers a wide variety of diagnostic and testing services.



Resources for Late Harvest Challenges - Fall 2009

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The 2009 harvest season continues to add challenge after challenge.  The University of Minnesota Extension has developed a website full of resources devoted to dealing with these challenges.

You will find these resources at Extension's late harvest resources web page.

Irrigated Corn Silage Plot Tour

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Friday, August 28, 2009
10:30 a.m.
Dan Dreyer Farm - Ottertail City

Tour Agenda:
Forage Production and Management Update
Forage Insects Past, Present, and Future
Alfalfa/Grass Stand Management
Hybrid Evaluation and Industry Update From Seed Companies

Alfalfa Weevil: Coming on Strong in West Central MN

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by Doug Holen, Extension Educator - Crops, Fergus Falls
and Phillip Glogoza, Extension Educator - Crops, Moorhead

Just a quick note to report a significant outbreak of alfalfa weevil in WC MN. It escalated over the weekend with a lot of spraying starting on Monday. We have fields in all stages with 1st crop still standing, cut alfalfa in windrow for some time, and 16" of 2nd crop regrowth. All fields have been hit hard. All alfalfa growers in west central MN should be checking for possible infestations.

By Phillip Glogoza, Extension Educator - Crops

The cool temperatures have delayed alfalfa weevil population development in the region. In west central MN, first cut got underway two weeks ago. As we move northwest, first cut may just be beginning for some. In some cases, cutting alfalfa may have removed significant eggs laid in stems, while in other sites young larvae are feeding in the growing terminals, whether it is regrowth or uncut alfalfa.

May 1 & 7 Alfalfa Stand Evaluation Workshops

Spring On-Farm Alfalfa Evaluation Workshops by University of Minnesota Extension Institute for Ag Professionals

Thorough and accurate assessment of alfalfa stand health and density is essential to profitable alfalfa production.  Spring green-up is a key time to take a detailed look at all alfalfa stands and make stand management decisions.  The University of Minnesota Institute for Ag Professionals (IAP) will host two on-farm alfalfa stand assessment workshops this spring in Minnesota.

Charla Hollingsworth, UM Extension Plant Pathologist, and Jeff Stein, South Dakota State University Plant Pathologist

Crown rust (caused by Puccinia coronata var avenae) and stem rust (caused by Puccinia graminis f.sp. avenae) are widespread and common on oat in the North Central (NC) state region. If environmental conditions promote rust development on susceptible hosts prior to grain fill, significant crop losses are likely to occur. While both diseases are responsible for repeated losses in oat, crown rust has a history of being the most damaging in this region because epidemics occur with more regularity.

2009 MN Forage Days February 9-13

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Paul Peterson, Neil Broadwater, Lisa Behnken, Doug Holen, Dan Martens, Krishona Martinson, and Russ Mathison, University of Minnesota; and Beth Nelson and Jenna Knoblauch, Midwest Forage Association

Harvesting results for a profitable future is the theme for the 2009 Minnesota Forage Days to be held at five locations in Minnesota the week of February 9.  The program is sponsored by University of Minnesota Extension and the Midwest Forage Association (MFA).  Dates and locations are:

  • Feb. 9, SWROC at Lamberton
  • Feb. 10, Floodwood Savannah Portage Restaurant
  • Feb. 11, Detroit Lakes ClubHouse Hotel (formerly Holiday Inn)
  • Feb. 12, Royalton American Legion
  • Feb. 13, Rochester UCR Heintz Center.
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