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Extension > Minnesota Crop News > April 2018

Monday, April 30, 2018

Forage topics for spring: Alfalfa assessment, establishment and emergency forages

by M. Scott Wells, Forage agronomist

Assessing alfalfa

taproots-on-shovel
Healthy alfalfa taproot on the left and damaged taproots on the right
A number of factors can contribute to winter damage of an alfalfa stand. These are all important to consider as spring assessments are made. The following elements may all play a role in winter survivability. As management options are considered, remember that injured alfalfa stands can exhibit delayed regrowth, but may be capable of recovering. Be careful not to rush into alternative options if the stand can be maintained for acceptable production.

Alfalfa assessment: Factors leading to winter injury

Emergency forages: Warm season grasses

grass-plots
Emergency forages at Rosemount, 2014.
In an effort to maximize forage production during the relatively short growing seasons of the upper Midwest, semi-dormant alfalfa varieties have been heavily promoted and widely adopted, which can increase the chance of winter injury and winterkill. During the 2012-2013 winter, significant acres of alfalfa in the state of Minnesota experienced winter injury and winterkill.

In years where alfalfa is injured by the winter and cool, wet springs persist, options to replant both annual row crops and forages can become more limited. Warm season grasses could provide an alternative emergency forage during such years.

Emergency forages: Warm season grasses

Alfalfa establishment

Since alfalfa production spans several years, it is important to start off with the highest productive stands possible. The UMN Forage Team adheres to the six following management strategies for optimal alfalfa establishment: (i.) field selection, (ii.) fertility management, (iii.) seeding dates, (iv.) field preparations and seeders, (v.) seeding depth, (vi.) seed-to-soil contact, and (vii.) seeding rates.

Alfalfa establishment
2017 Alfalfa Field Crop Trials Results


For more information, visit the University of Minnesota's Forage production website.

Friday, April 27, 2018

Answers to 5 Spring Nitrogen FAQs


Fabian Fernandez, Nutrient Management Specialist
Jeff Vetsch, Soil Scientist
Brad Carlson, Extension Educator

After crazy weather in early spring, it’s finally time to get out in the fields. We’ve gotten a lot of questions about spring nitrogen lately. Here are the frequently asked questions we get about nitrogen management this time of year.

Thursday, April 26, 2018

To treat or not to treat: Should fungicidal seed treatments be applied to small grain seed this year?

Madeleine Smith, Extension small grains pathologist

field-with-spotty-wheat-stand
Root rots causing poor stand establishment in wheat. Photo: A. Friskop
At this time of year decisions are being made about whether to treat small grains seed with fungicide or insecticidal seed treatments before planting.

Fungicides applied on seed can help protect stand establishment if there are fungal diseases present in the soil, or if seed saved from the previous season is infected with Fusarium head blight or smuts. Infection by fungal pathogens at or just after germination can cause seedling loss. If seedlings do not die, they can have poor vigor, due to the inability to efficiently take up water and nutrients.

Monday, April 23, 2018

Don't compromise on best practices for rotating alfalfa to corn when field work is delayed

By Jeff Coulter, Extension Corn Agronomist

corn in field
There are many advantages to planting corn after alfalfa, including greater yield potential, reduced nitrogen needs from fertilizer or manure, and reduced pest pressure compared to when corn follows other crops. The degree to which these and other benefits are achieved is contingent upon successful termination of alfalfa, as alfalfa can greatly complete with corn for water and nitrogen. Therefore, avoid compromising on best practices when rotating alfalfa to corn, even when spring field work is delayed.

Calibrating Your Grain Drill

In last week’s post, I mentioned that small grain seeding rates should be increased once we are past the optimum time to offset the loss of tillers and ultimately reduced yield potential caused by the delayed planting date.  Consequently, you need to recalibrate your drill. Recalibrating your drill every spring is a good practice anyway as seed size and weight of different seed lots vary year-over-year and among varieties.

Modern air seeders and drills with central seed metering are relatively easy to calibrate and your user manuals have detailed instructions on how to calibrate them.  Older double disk drills are a little different story and the seeding rate tables seeding rate tables found in your operator's manual or on the inside of the seed hopper lid are a guideline at best.

Calibrating your drill in the yard is an easy way to take the guesswork and some of the stress out of it prior to getting in the field.  By measuring the circumference of the press wheel or drive wheel and then turning the wheel a certain number of times we can calculate the distance traveled.  This number multiplied by the row spacing gives the area seeded.  Catching and weighing the seed dropped by a few of the metering wheels will then allow you to calculate the seeding rate in lbs. per acre for each lot. 

The Samuel Roberts Noble Foundation from Oklahoma created a useful YouTube video that explains the steps described above very well. A cover story in Prairie Grains issue 7 describes how the Ramstad brother from Ada built a device that hooks an electrical motor on the drill frame to drive the press wheel the correct number of revolutions.



Friday, April 20, 2018

Weather Delays Corn Planting but Optimal Window Remains Open

By Lizabeth Stahl, Jeff Coulter, and Dave Nicolai

Much of Minnesota has been covered in snow past mid-April and it will take some time for field conditions to dry enough for field work and planting to begin. Farmers are encouraged to consider the following as they wait for the 2018 corn planting season to begin.

Tuesday, April 17, 2018

Nutrient Management Podcast: Spring Nitrogen Outlook 2018


Spring is upon us! While there still may be snow on the ground, on this episode we have your spring nitrogen outlook. Guests Brad Carlson, Fabian Fernandez, Dan Kaiser, Greg Klinger and Anne Struffert answer some of your most frequently asked questions, including: How much N should I apply this spring? If I applied N in the fall, how much have I lost going into spring? What about starter fertilizers? How much N should I apply as starter? Is a preplant soil N test worth it this year? Should I use a nitrification inhibitor? What should I do about anhydrous if soil is too wet?

Monday, April 16, 2018

Respirator fit testing webinar

Do you have employees who need to wear a respirator this year? Or would you like to be a fit testing resource to your community? University of Minnesota, Extension is hosting a free fit test training webinar in collaboration with 3M on April 30th. 

Image: 3M

Evaluating Your Winter Wheat and Rye Stands

As wintery weather persists, you may wonder if your winter wheat or rye has survived this winter.  If you are really anxious or bored, you can dig up some crowns across the field and cut them longitudinal (lengthwise) with a very sharp knife or a safety razor blade. If the crowns look white/yellow to light green, they are healthy and have survived the winter to date. If you find crowns that have turned tan to brown and soft, they likely did not survive this winter.  A second method to check whether seedlings are alive is by trimming the roots and leaves down to about ¼  to ½ ” above and below the crown. Place these seedlings on a wet paper towel and place the towel in a Ziploc bag or plastic container that can be sealed. Place the container at room temperature and check for regrowth in 48 hours. Viable seedlings will show regrowth almost immediately (Photo 1). 


Photo 1 - Regrowth of young winter wheat seedlings after 36 hours incubation in a Ziploc bag at room temperature (photo courtesy of Blake Vandervorst)

Unfortunately, checking a single or a few crowns does not tell the whole story as winterkill is often patchy across a field (Photo 2).  To determine whether you need a plan B for these fields requires you to wait until the field starts to green up sufficiently in order to do a reliable stand count.  The more protected areas will green up first, while bare knolls or lower lying areas where water or ice may have been present sometime during the winter and early spring will be slowest to green up.


Photo 2 – Area with partial and uneven winter kill (photo courtesy of Joel Ransom).

To do a stand count, use one of the following two methods:

1.        Count the number of plants in a foot of row at several locations in the field.  Take an average and convert in plants per acre using Table 1.

2.        Take a hula-hoop, let it fall, and count the number of plants inside the hoop.  Repeat this at random several times across the field and calculate an average.  Use Table 2 to convert the count to an approximate population per square foot or acre.


Table 1 - Average number of plants per foot of row for different row spacing and plant densities per acre.
                                                                               

Plants per acre (times 1 million)
Row Width
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5









6”
9.2
10.3
11.5
12.6
13.8
14.9
16.1
17.2
7”
10.7
12.1
13.4
14.7
16.1
17.4
18.7
20.1
10”
15.3
17.2
19.1
21.0
23.0
24.9
26.8
28.7
12”
18.4
20.7
23.0
25.3
27.5
29.8
32.1
34.4


Table 2 - Adjustment factors to multiply the number of plants inside a hoop and convert the number into the number of plants per acre.

Hoop Diameter
Multiply by


30”
8,900
32”
7,800
34”
6,900
36”
6,200
38”
5,500



Uniform stands of 17 plants per square foot or approximately 750,000 plants per acre are sufficient to keep and do not require a plan B.  Consider replanting only those areas of the field where stands are below the threshold with, for example, spring wheat.  No-till seeding HRSW into standing HRWW is possible but creates some challenges later in the season because the two crops will reach growth stages at different times and complicate not just harvest but also the timing of herbicides and fungicides.

Friday, April 13, 2018

Small Grains: An easier way to establish (and grow) cover crops

Jochum Wiersma, Scotty Wells, and Jared Goplen

Establishing cover crops in corn and soybeans is not without its challenges in Minnesota.  There is little growing season left after harvest and soil moisture and herbicide carryover can often limit the ability to get a good cover crop stand when interseeding mid-season. In response to these growing season limitations, new interseeding technologies offer the promise to overcome some of the establishment issues in Minnesota (click here for more information). Even with the most advanced interseeding technologies, cover crop establishment success will be greater following short season crops. Wheat, barley, and oats make establishing cover crops much easier. There is plenty of growing season left following small grain harvest for reliable cover crop establishment. Oftentimes cover crops seeded following small grains accumulate enough biomass to be grazed or harvested for forage in the fall. 

Small grains also provide the opportunity to interseed cover crops. After all, interseeding alfalfa with oats is a common method to establish alfalfa. This approach can easily be extended to other legumes, including clovers and even grasses like annual ryegrass.  A common practice in NW Europe is to spread annual ryegrass with a fertilizer spreader over the top of winter wheat in early spring.  This strategy tends to work well for annual ryegrass and other species that require shallow seeding and light to stimulate germination. This strategy can probably be used successfully to interseed cover crops into wheat, barley, or oats in Minnesota.  

The biggest challenges when interseeding legumes in small grains is effective weed control, as many legume species are quite sensitive to the commonly used broadleaf herbicides. It is also important to select the proper legume species to avoid crop competition and harvest difficulty. Legumes like hairy vetch become very competitive when the small grain starts to mature, even to the point where plants impede harvest by reaching the top of the small grain canopy prior to harvest. Alfalfa and red clover are more appropriate choices to interseed with small grains, as UMN research has found they do not impede grain harvest and do not negatively affect hard red spring wheat yield. Other agronomic practices, including fertility management and seeding rates, can remain the same for interseeding small grains when compared to the practices for monocultures of wheat, barley, or oats.   More information on previous UMN research on intercropping alfalfa, red clover, and hairy vetch in hard red spring wheat can be found here.

Thursday, April 12, 2018

Research on Woodland Management and Soybean Aphid: Cooperating Growers Needed

by Marcella Windmuller-Campione (Assistant Professor, Dept. of Forest Resources) and Robert Koch (Assistant Professor, Dept. of Entomology)

Looking for soybean growers in central and southern Minnesota to participate in a research study on soybean aphid population levels and buckthorn density in 2018

While there are several options for managing the destructive soybean aphid, including insecticides
and aphid-resistant soybean varieties, these options focus solely on the soybean field. However, it is very likely that buckthorn is lurking (and reproducing!) in your woodland or an adjacent publicly own forest, proving the required overwintering habitat for soybean aphid. Research in Ontario, as well as in Minnesota, has observed the relationship between proximity of buckthorn and early season
soybean aphid population levels. What has been little explored is if this relationship varies with buckthorn density – Does higher density buckthorn result in higher early season soybean aphid populations? If so, are there management techniques that we can implement to reduce buckthorn density, which could possibly reduce soybean aphid populations, thus improving quality and yield for soybean growers?  These questions require an interdisciplinary approach, bringing together research
faculty, Extension educators, and soybean growers with expertise in forestry, entomology, and agriculture.
Image of European buckthorn, which is the overwintering host for soybean aphid
(photo credit: Paul Wray, Iowa State Univ., Bugwood.org).
Do you have a soybean field adjacent to a woodland in central or southern Minnesota?... 

Wednesday, April 11, 2018

Why you need to use a preemergence herbicide on sugarbeet fields in 2018

Tom Peters, Extension sugarbeet agronomist


Waterhemp Cotyledons are more rowboat shaped than other pigweed species. True leaves are long and narrow (lanceolate) and are waxy and dark green. There are no hairs on the plant.
Waterhemp is the most widespread weed control challenge in sugarbeet. Growers attending the 2018 technical seminars and participating in the Turning Point survey of weed control and production practices reported waterhemp as their most important weed control challenge on 237,600 acres or over 35% of sugar beet fields in Minnesota and eastern North Dakota.

Sugarbeet planting date dictates the weed control strategy for waterhemp control. In 2017, many acres of sugarbeet were planted between April 10 and April 20. Early planting enables sugarbeet to grow to the 2-lf stage, or the sugarbeet growth stage when Dual-Magnum, Outlook, and Warrant is applied, before waterhemp gemination and emergence in mid-May (POST to sugarbeet, PRE to waterhemp). Split lay-by application of chloroacetamide herbicides or first application at the 2-lf stage followed by a repeat application 14 to 21 days later is the preferred approach for waterhemp control for early planted sugarbeet (Table 1).

Tuesday, April 10, 2018

When is late too late?

It doesn't look like anyone will be doing any fieldwork in Minnesota anytime soon.  The question when it will be too late to seed small grains, therefore, is becoming a bit more urgent.  

Wheat, barley, and oat are cool-season annuals and are most productive when they grow and develop during cool weather.  The yield potential of these cereals is largely determined by the 6 leaf stage.  Cool temperatures during this period are particularly important for the development of a high yield potential.  For example, the number of tillers that ultimately produce grain at harvest declines as planting is delayed (Figure 1).  The number of spikelets per spike is determined during the 4 to 5.5 leaf stage (Figure 2).  Spikelet numbers are negatively correlated with temperature; spikelet numbers are greater when temperatures during the 4-5.5 leaf stages are cool.  

Figure 1 – The effect of planting date for on the number of heads per square feet of hard spring wheat at harvest in Langdon, ND (data and graph courtesy of Terry Gregoire, Area Agronomist, NDSU).



Figure 2 - The effect of maximum daily temperatures on the number of spikelets per spike that are initiated between the 4 and 5.5 leaf stage of spring wheat in Langdon, ND (data and graph courtesy of Terry Gregoire, Area Agronomist, NDSU).



Because of the expectation that average temperatures will be higher as we plant later, development of the crop will speed up too. The number of heat units required for a plant to move to the next phase of development will accumulate faster.  This forces development along faster and causes the plant to have less time to grow. Plants end up with fewer tillers, smaller heads, and fewer and smaller kernels per head, cutting into our yields.   

To improve the odds of high grain yields is to ensure that the tillering and head initiation phases occur during relatively cool temperatures is by planting early.  Early planting is key to raise wheat, barley, and oats in Minnesota successfully (Table 1)

Table 1 - The optimum and last recommended seeding dates for small grains in Minnesota.    
Minnesota
Optimum
Last Planting Date:



South of US Hwy 12
South of MN Hwy. 210
1st week of April
2nd week of April
1st week of May
2nd  week of May
South of US Hwy. 10
3rd week of April        
3rd week of May
South of US Hwy. 2     
4th week of April
4th week of May
South of Canadian Border
1st week of May         
1st week of June

Research has shown that, on average, yields decreased 1% per day when planting is delayed past the optimum planting date.  Planting after the last possible date is not recommended because of the odds that grain yield and quality (test weight) will be dramatically reduced due to heat stress.

You can partially offset this yield loss by increasing the seeding rate and ensuring that you have more main stems per unit area. The recommendation is to increase the seeding rate by 1 percent for every day after the optimum planting window.


The last possible date for planting is not chiseled in stone. The odds of a high(er) grain yield with excellent test weight are less in our favor with every day seeding is delayed past our optimum planting windows simply because of the expected temperatures later in the growing season.   

New App for MN Farmers, Consultants: Midwest Stink Bug Assistant

Bill Hutchison, Theresa Cira and Bob Koch

stink-bug
Figure 1. Look for the Midwest Stink Bug Assistant screenshot to download the app.
A free IOS and Android app has been developed by the University of Minnesota Extension IPM Program, in partnership with the Minnesota Invasive Terrestrial Plants and Pests Center and Purdue University (Fig. 1). The app can be downloaded here, for both Apple and Android platforms.

The main focus of the app is to facilitate early detection and reporting of the invasive Brown Marmorated Stink Bug (BMSB; Halyomorpha halys), but it also helps users identify native stink bug species common to the Midwest region. This free app, Midwest Stink Bug Assistant, will allow farmers, crop consultants, and the general public to become comfortable distinguishing stink bugs from other bugs and identifying common stink bugs.

Monday, April 9, 2018

Spring Nitrogen Outlook

Guests Brad Carlson, Fabian Fernandez, Dan Kaiser, Greg Klinger and Anne Struffert are here with a spring nitrogen outlook. On this episode, we answer some of your most frequently asked questions, including:
  • How much N should I apply this spring?
  • If I applied N in the fall, how much have I lost going into spring?
  • What about starter fertilizers? How much N should I apply as starter?
  • Is a preplant soil N test worth it this year?
  • Should I use a nitrification inhibitor?
  • What should I do about anhydrous if soil is too wet?
For more the latest on nutrient management, follow us on facebook at facebook.com/UMNNutrientMgmt or Twitter at twitter.com/UMNNutrientMgmt.

Handling Variability in Manure Nitrogen with Manure Analysis


Gregory Klinger, Extension Educator
Melissa Wilson, Extension Manure Specialist

One of the big challenges when using manure as a fertilizer source is knowing the amount of plant nutrients that are present and available in the manure. This uncertainty increases the risk of over-applying or under-applying nutrients to the field. The risk is greatest with nitrogen (N), which can easily move out of manure during storage and is a source of drinking water concerns. However, there are ways that producers can lower that risk. One of those ways is by getting manure tested.

2018 Sugarbeet Production Guide

Ashok Kumar Chanda, Extension plant pathologist

The Sugarbeet Production Guide provides useful information to assist you in making timely management decisions in 2018. It contains an excellent overview of recommended practices, but for more detailed discussions of weed control, soil fertility, insect and disease control, and other aspects of sugarbeet production in Minnesota and North Dakota, see past issues of the Sugarbeet Research and Extension Reports available at the web site (http://www.sbreb.org).

Sugarbeet Rhizoctonia Management Plan for 2018



By Ashok Chanda (Assistant Professor & Extension Sugarbeet Pathologist), Department of Plant Pathology and Northwest Research and Outreach Center, University of Minnesota – Twin Cities

Ashok Chanda can be reached at 218-281-8625 or achanda@umn.edu or Twitter @BeetPath

Hopefully the official sugarbeet planting season will start in a couple of weeks in MN and ND and as usual there may be a lots of questions on your mind about how to get a hold on Rhizoctonia diseases, this is also confirmed by the highest number of Rhizoctonia samples diagnosed in our laboratory during the past 3 years. If this year’s planting is delayed due to weather, fields will be at high risk for Rhizoctonia, as warm soil favors development of Rhizoctonia. Here are some things that can help you to develop your customized Rhizoctonia Management Plan for 2018.

Wednesday, April 4, 2018

Don't Apply Commercial Fertilizers to Snow-covered Frozen Soils


Dan Kaiser, Extension Nutrient Management Specialist

The recent snows across the state may be spurring concerns with fertilizer application this spring. Application of any fertilizer source should not occur when the ground is still frozen, especially on top of snow. All commercial fertilizer products are water soluble and will dissolve readily in liquids. There is an extreme risk for fertilizer to run off the field with snow melt, regardless of the fertilizer source. In order for the soil to retain nutrients, they need to come in contact with soil particles. This reaction won’t happen in frozen soils and any fertilizer applied will move with water off the field or to low areas of the field. Environmental issues aside, applying fertilizer on frozen or snow covered soils presents a significant economic risk, as that purchased material won’t be available to the crop when it’s growing in the field.

Monday, April 2, 2018

Why Do We Need a Soybean Nitrogen Credit?


Greg Klinger, Extension Educator
Shane Bugeja, Extension Educator

In a corn-soybean rotation, the corn will need less nitrogen (N) following the nitrogen fixing legumes than in a continuous corn operation. Thus, a nitrogen “credit” is applied to manage N properly. Most people account for soybean credits when making fertilizer decisions, but often assume the extra nitrogen is coming from the soybeans themselves. The real reason is a bit more complicated and involves several factors including soil nitrogen availability, residue amount, and microorganism preferences.

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