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Extension > Minnesota Crop News > 2017

Wednesday, August 23, 2017

Mow fenceline weeds now to prevent seed production

By: Jared Goplen and Dave Nicolai

Mow Fenceline Weeds
Photo 1: Mow fencelines now to minimize deposits to the weed seed bank. Photo: Jared Goplen.
As summer field activities wind down, harvest will soon be in full swing. Take the time now to mow fenceline weeds to prevent or minimize seed production. Fencelines are often where weed infestations start. By eliminating fenceline weeds, we prevent combine harvesters from picking up weed seeds from the field edges and pulling them into the field, where they can be further spread by harvesting and tillage equipment.

Tuesday, August 22, 2017

Update: Wheat Stem Sawfly infestation levels found in Polk County

prepared by Phillip Glogoza, Jochum Wiersma and Ian McRae

Wheat stem sawfly (WSS) are being found at significant levels in Polk County. Field surveys were conducted from August 14 to 18, 2017 to learn more about the levels of infestation and the possible size of the area impacted. 

The inspected fields had infestations on the field margins ranging from a low of 0 to a high of 15 WSS/row foot. Every field inspected had fewer infested stems as sampling moved further into the field. Edge effects are pretty strong with this insect as they overwinter in stubble and migrate to nearby wheat the next year.

Thursday, August 17, 2017

Your Guide to Profitable Sulfur Fertilization in Spring Wheat


Dan Kaiser, Extension Soil Fertility Specialist

The major cause of sulfur deficiencies in crops is a lack of mineralized S in the soil. Research and recommendations in Minnesota have shown well-documented yield increases for corn with the application of sulfur, but what about wheat? Recent research funded by the Agricultural Fertilizer Research and Education Council and the Minnesota Wheat Research and Promotion Council shows us that sulfur applications can benefit wheat yield and protein concentration. Here are some tips and recommendations for sulfur applications in spring wheat based on that research.




Tuesday, August 15, 2017

Plan to attend the Strip-till Expo on September 6

Jodi DeJong-Hughes, Extension educator

strip-till
Plan to attend this year’s Strip-Till Expo on Wednesday, September 6th at the University of Minnesota - North Dakota State University Tillage Research Trials, west of Fergus Falls, MN.

A hallmark of the day will be the side-by-side field demonstrations in the afternoon. Eight strip-till implement manufacturers will demonstrate their equipment, including Dawn, ETS, Gates Mfg., Kuhn Krause, Orthman Mfg., Schlagel, Twin Diamond, and Yetter.

Factors influencing dicamba volatility

Jeff Gunsolus, Extension weed scientist

Earlier Crop News articles focused on dicamba’s potential routes of injury, injury symptomology, soybean sensitivity and yield loss potential. In this article, I would like to explore in greater detail the factors that could contribute to dicamba volatility's role as a potential route of injury. I will be working off the assumption that the primary cause of dicamba volatility is due to degradation of the new dicamba formulations to dicamba acid, dicamba’s most volatile form. A 1979 Weed Science publication by Behrens, R. and W. E. Lueschen titled "Dicamba Volatility" will serve as my reference (Weed Sci. 27:486-493).

Target weeds after small grain harvest

By Jared Goplen, Tom Peters, and Dave Nicolai

waterhemp-in-wheat-stubble
Waterhemp in a wheat stubble field in Ottertail Co., Minnesota. Photo: Dave Nicolai
One of the many benefits of including small grains in crop rotations is improved broadleaf weed control and breaking up weed lifecycles. Although freshly harvested small grain fields have a clean look, they often have weeds hiding in the stubble. The most prominent weeds in stubble fields are often late-emerging weeds like waterhemp and other pigweed species that emerged after early season herbicide applications were made. Control escaped weeds now to prevent seed production and weed seed bank replenishment.

Monday, August 14, 2017

When good butterflies go bad

Bruce Potter, IPM specialist and Bob Koch, Extension entomologist

thistle-caterpillar
Photo 1. Thistle caterpillar leaf feeding and webbing. Photo: Bruce Potter
The second 2017 MN generation of thistle caterpillars continue to cause concern in some soybean fields. Most of the reports of Minnesota high populations are from SW, SC, C, and the WC part of the state.

Adults and egg-laying are now tapering off but more than two weeks of painted lady butterfly egg-laying activity means that there is a wide range of larval sizes out there.

Wheat Stem Sawfly Causing Problems in Polk County Wheat Fields

Prepared by Phillip Glogoza, Jochum Wiersma and Ian McRae

wheat-stem-sawfly
Figure 3. Wheat stem sawfly cut stems were so extensive, the cut stems could be picked up as a bundle on the edge of this wheat field west of Crookston, MN.
As wheat harvest moves northward, we are detecting infestations of Wheat Stem Sawfly in fields in Polk County. Recent storms and strong winds have helped bring these problems to front and center.

Farmers have noticed lodged stems, particularly on field margins, where in some cases plants are 100% lodged for 50+ feet from the edge inward. In those cases, the cut stems could be grabbed and picked up in a bundle (Figure 3) and the stubble below was all cut (Figure 4). As we inspected the interior of these fields, the percent lodging, declined, but there was still evidence of Wheat Stem Sawfly damage.

Friday, August 11, 2017

What the Research Says About Post-tassel Nitrogen Applications


Fabian Fernandez, Nutrient Management Specialist
Paulo Pagliari, Soil Scientist

Optimal nutrient application timing can be hard to nail down. Should you apply everything at the beginning of the season? Sidedress? If so, when? Many people wonder about nitrogen applications late in the season, even after post-tassel, as a way to increase yield. The basic thinking is that the crop still needs to take up half of its total N at this point in the growing season. The truth is, in locations with a shorter growing season, like Minnesota, we have no evidence that post-tassel N applications have any advantage.

Tuesday, August 8, 2017

Response of soybean yield to dicamba exposure: A Research-based report

by Jeff Gunsolus, Extension weed scientist

dicamba-drift-soybean
Xtendimax drift onto non dicamba-tolerant soybean. Photo: Liz Stahl
As you continue to assess and document the impact of dicamba injury on soybean yield, I thought it would be timely to make you aware of an excellent summary of Dr. Andy Robinson’s research conducted when he was a graduate student at Purdue University. This summary came from Purdue Extension and was authored by Joe Ikley and Bill Johnson: https://z.umn.edu/2vhs

The published manuscript can be accessed at: https://z.umn.edu/dicamba-purdue

Monday, August 7, 2017

Late season weed escapes in soybeans? What Now?

By Jared Goplen, Dave Nicolai, Lisa Behnken, Jeff Gunsolus

giant-ragweed
Giant ragweed escapes in soybean. Photo: Dave Nicolai
Despite your best weed-control efforts this year, you still ended up with patches or fields with weeds coming through the crop canopy. Now that August has rolled around, what options are available to control weeds and prevent them from going to seed? What can we do differently to prevent this problem next year? August is a good time to evaluate your current weed management plan and develop strategies for next year.

Tuesday, August 1, 2017

Assessing and documenting yield loss due to dicamba injury in soybean

by Jeff Gunsolus, Extension weed scientist

dicamba-injury-soybean
Photo 1. Leaf cupping symptoms of dicamba injury in soybean. Photo: Bruce Potter
As we enter August, the big unknown in fields presenting dicamba injury symptoms will be dicamba’s impact on soybean yield. Unfortunately, due to the sensitivity of non-Xtend soybeans to dicamba, injury symptoms are not reliable indicators of yield loss. The level of yield loss depends on exposure at vegetative or reproductive stage of growth, persistence of injury symptoms, and growing conditions post-exposure.

Production questions to be addressed at Cover Crop and Soil Health Learning Tour

by Lizabeth Stahl

cover-crop
What impacts can we expect on soil health and productivity with cover crops, reduced tillage and/or a more diversified cropping system? Should I adjust my weed or nutrient management program when interseeding cover crops into corn or soybean? How can I best fit cover crops and/or reduced tillage into my operation?

Learn about these questions and more from researchers, farmers, and educators working with cover crops and soil health by attending the "Cover Crop and Soil Health Learning Tour," Friday, September 8th, at the Bruce and Mary Brunk farm, 23068 220th Street, Rushmore.

Research Shows N Rate in Sweet Corn Higher than Current Recommendations


By Carl Rosen, Professor and Head Department of Soil, Water and Climate
Vince Fritz, Professor, Horticultural Science

New research conducted at the Southern Research and Outreach Center in Waseca shows that the optimal N application rate for new sweet corn hybrids following soybeans in non-irrigated, on medium- to high-organic matter soils is higher than the current recommended rate of 110 lbs N/ac.

Monday, July 31, 2017

Pyrethroid resistant soybean aphids: What are your control options?


Bruce Potter (Extension IPM Specialist, U of MN), Robert Koch (Extension Entomologist, U of MN), Phil Glogoza (Extension Educator – Crops, U of MN), Ian MacRae (Extension Entomologist, U of MN), and Janet Knodel (Extension Entomologist, NDSU)

We are receiving an increasing number of reports of pyrethroid insecticide failures for soybean aphid management from northwest and central Minnesota, and northeastern North Dakota this year. However, many areas of Minnesota and North Dakota still have low, non-yield threatening aphid numbers and scouting should continue to determine when to apply insecticides.

In this article, we review the insecticide groups used for soybean aphid control (Table 1) and discuss the potential role of and challenges associated with insecticide mixtures.

Wednesday, July 26, 2017

Uncovering dicamba herbicide's wayward ways

by Jeff Gunsolus, Extension weed scientist


Leaf cupping symptoms of dicamba injury in soybean. Photo: Fritz Breitenbach
Dicamba injury to non-target soybeans has been widely reported in south central and southwest Minnesota. Symptoms range from cupping and strapping of newly emerged leaves to height reduction and injury to growing points. At low dicamba concentrations, symptoms were slow to emerge, showing up 14 to 21 days after exposure. The big unknown, of course, will be impact on soybean yield, which will require negotiations now to determine the most accurate in-field yield comparisons later.

Monday, July 24, 2017

Estimating Grain Small Grains Grain Yields

The USDA-NASS' July 1 yield forecasts for barley, oat, and spring wheat were 67, 71, and 61 bushels per acre, respectively.  This would mean a new state record for spring wheat, while the forecast for barley and oats are 10 and 7 bushels off the records set in 2015.

To estimate yield the USDA-NASS collects farmer's assessment of yield prospects throughout the growing season, i.e. the USDA-NASS asks producers to predict their final yield. At first glance, this may seem a bit unscientific and not very accurate. The statistical methods that are used to crunch the collected data and have it confess a forecast, however, are robust and because enough producers are surveyed, the forecasts have been proven predictive at the aggregate level.  This is, in a way, a testament that you each know you crop and operation pretty well. The completely methodology can be found here.

Luxury Uptake of Boron: How Much is Too Much?


By Dan Kaiser, Extension Soil Fertility Specialist

The ultimate goal of nutrient management is to ensure that the plant has enough nutrients to produce maximum potential yield. This involves monitoring soil nutrients and crop uptake, and often supplementing nutrients that the crop is lacking. But what happens when the plant takes up more than enough of a certain nutrient? That’s called luxury uptake. Though it isn’t usually a problem for crops, it can become an issue if a nutrient reaches toxic levels in a plant. In Minnesota, the main concern is with Boron in soybeans and other broadleaf plants.

Friday, July 21, 2017

Soybean aphid infestations and reports of failures of pyrethroid insecticides to control soybean aphid



Robert Koch (Extension Entomologist), Ian MacRae (Extension Entomologist), Bruce Potter (Extension IPM Specialist), and Phil Glogoza (Extension Educator – Crops)

By now you should be scouting your soybean fields for soybean aphid on a regular basis.  Soybean aphid can be found in most fields throughout the state and populations have reached economic threshold (250 aphids per plant) in some fields in northwest Minnesota and have require insecticide application to protect soybean yield.  In northwest Minnesota (especially around Norman County), applications of pyrethroid insecticides are failing to adequately control aphid populations in some, but not all, fields.  

Thursday, July 20, 2017

The Dicamba Dilemma: Facts and speculations

Used with permission by Aaron Hager, University of Illinois

dicamba-injury-soybean
Dicamba injury to soybeans in a southwestern Minnesota field. Photo: Stephan Melson
Dicamba injury to non-target crops has dominated Extension discussions this week. Non-tolerant soybeans are extremely sensitive to this chemical and damage has been reported in a number of fields throughout the state. The following article by Dr. Aaron Hager at the University of Illinois echoes observations we have been making in Minnesota and summarizes injury symptoms on soybean, possible routes of exposure, and potential yield effects. His article is reprinted in its entirety:

Wednesday, July 19, 2017

Herbicide Mode of Action and Crop Injury Symptoms at the University of Minnesota Field School for Ag Professionals

by Dave Nicolai, IAP Program Coordinator

This year at the Field School, participants will have two opportunities to learn, re-learn or fine-tune their skills in linking visual symptomology to the common herbicide modes of action commonly used in corn and soybean and gain in-depth knowledge of growth regulator herbicide movement and symptomology in soybean.

Weed management has changed dramatically in recent years. The large number of herbicide options—new products, old products with new names, new formulations of old products, premixes, and generics—can make weed control appear to be a difficult and confusing task. Knowing and understanding each herbicide’s mode of action is an important step in simplifying and selecting the proper herbicide for each crop, diagnosing herbicide injury, and designing a successful and durable weed management program for a farmer’s production system.

Tuesday, July 18, 2017

Lunch and Learn Webinar: Managing Ash Content in Hay

Krishona Martinson - University of Minnesota

On Wednesday, August 23, 2017 from 12:00 to 1:00 pm (central time), the University of Minnesota will host a free webinar titled “Managing Ash Content in Hay”. Dr. Marvin Hall, Professor of Forage Management from Penn State University, and Abby Neu, Extension Educator from the University of Minnesota Extension, will present the webinar.

Hay Rake Impacts Ash Content in Alfalfa Hay

Abby Neu, Craig Sheaffer, Scotty Wells and Krishona Martinson, University of Minnesota; Marvin Hall and Dan Kniffen, Pennsylvania State University; and Dan Undersander, University of Wisconsin.

Summary: Using a hay merger or sidebar rake to combine swaths resulted in less ash content compared to a wheel rake; however, rake-type rarely resulted in differences in forage nutritive value. In addition to wide swaths, cutting heights ≥2 inches, and flat mower knives, the use of a hay merger or sidebar rake can be added to the list of best management practices to reduce ash content in alfalfa hay.

Pre-harvest Management of Small Grains

To save time and money most of you prefer to straight cut your wheat, barley, rye or oats.  The allow for straight cutting the crop has be evenly ripe across the field and the straw and grain has to be dry enough that it will feed through the combine.

Waiting for a whole field to dry down poses a risk for the portion of the field that is already harvest ripe, including sprout damage, straw breakage and lodging. To even out dry-down and/or speed up dry-down you have two basic options. Swathing or windrowing, at one time, was the default operation that signaled the beginning of harvest.  A second preharvest option is an application of glyphosate at the hard dough stage.

Glyphosate is labeled as a harvest aid to control late emerged weeds that may interfere with harvest. The RoundUp PowerMax II  label doesn't define it as a desiccant. Research has shown that glyphosate applied with or without ammonium sulfate may hasten drydown of the wheat crop if conditions for drydown are adverse. With a preharvest interval of 7 days, a couple of days, at the most, may be gained. Previous Minnesota Crop News post provide details about swathing and preharvest glyphosate.





White Heads

Jochum Wiersma, Ian MacRae, and Madeleine Smith

Is not the reincarnation of the Detroit rock due the White Stripes but a phenomenon that often can be seen this time of year in wheat fields are they are starting to ripen.  The causes of these premature ripened heads are varied and a diagnostic key can be found here.

People of commented that especially the wheat stem maggot is more prevalent this year and my travels to the different field trials across the state confirm this. The seemingly high numbers of wheat stem maggot may be related to the mild winter conditions.  Several insect pests that overwinter in Minnesota have had comparatively high and early populations this year.

Incidence will generally be worse along field edges and taper off as you walk further into the field.

Friday, July 14, 2017

4 Steps to More Effective Tissue Sampling


Daniel Kaiser, Extension Soil Fertility Specialist

For over 50 years, the practice of plant tissue sampling has been used to determine the status of nutrients in crops. More recently, there has been a movement to use tissue sampling to determine “hidden deficiencies” in the crop. While tissue analysis represents just one tool in the toolbox for managing nutrients and should be viewed like a report card, it can provide useful information in diagnosing problems when done properly. Here are the 4 things you need to make the most out of tissue analysis.

Monday, July 10, 2017

Register now for 2017 Field School for Ag Professionals

By Dave Nicolai, IAP Program Coordinator

2017-field-school
View video to learn more about Field School.
Agronomy training available this summer at the University of Minnesota Extension's 2017 Field School for Ag Professionals

The 2017 Field School for Ag Professionals will be held on July 27 - 28 at the University of Minnesota Agriculture Experiment Station in St. Paul. Field School for Ag Professional which is the summer training opportunity that combines hand-on training and real-world field scenarios. The two-day program focuses on core principles in agronomy, entomology, weed and soil sciences on the first day to build a foundation for participants and builds on this foundation with timely, cutting-edge topics on the second day.

Field Studies: Setting up a Trial

Josh Coltrain, Kansas State University; Sara Berg, South Dakota State University; Lizabeth Stahl, University of Minnesota; John Thomas, University of Nebraska Lincoln

plot-comparison
Photo 1. Example of an on-farm trial.
Higher yields, greater efficiency, reduced environmental impact!  This may sound like a used-car dealership sales pitch, but it could represent the objectives that make an operation sustainable. Increasingly, farmers are generating on-farm research data that encompass a wide-range of practical topics.  However, setting up those experiments so that the data is statistically valid is not necessarily common knowledge.

Thursday, July 6, 2017

Short(er) Spring Wheat Crop = Lower Grain Yield?

Some of you have noticed and commented that the spring wheat crop is shorter when compared to the last few years and subsequently questioned its yield potential. A few weeks ago, Dr. Joel Ransom wrote a nice article in the Crop & Pest Report explaining why the spring wheat crop was shorter and whether its yield potential had already been reduced.  

The physiology of grain fill has been well researched and we have a good understanding how temperature and droughts tress affect grain fill and grain quality. Table 1 summarizes the results of one of the published studies that illustrates how daytime and nighttime temperatures affect the length of the grain fill period and ultimately yield. The bottom-line is that higher nighttime temperatures are more detrimental than the maximum daytime temperatures.

Just in the last two days has the grain fill suffered some heat-stress, as maximum temperatures had not yet reached above 85F in the two weeks prior while minimum temperatures were mostly in the fifties in the same period (Table 2). 

Therefore, I am optimistic about this year’s yield potential, despite the shorter than normal crop as the first weeks of grain fill have been favorable, allowing for a larger proportion of the grain being produced de novo rather than being recycled from the shorter canopy.

The only caveat in this optimism is that the crop didn't suffer any other stresses these past two weeks. Drought stress poses the greatest threat but the cooler temperatures also reduced the crop's daily water consumption considerably.


Table 1 - Effect of daytime and nighttime temperatures on the length of the grain fill period and the average kernel weight (after Altenbach et al, 2003)

Tday
(oF)
Tnight
(oF)
Length Grain Fill
(days)
Thousand Kernel Weight (grams)
75
63
40
50
99
63
30
40
99
82
18
20


Table 2 – The daily maximum and minimum temperatures at 3 NDAWN locations in NW Minnesota and the number of days the temperatures were outside the optimum range for grain fill for spring wheat.
Date
Humboldt
Ada
Campbell
Tmax
Tmin
Tmax
Tmin
Tmax
Tmin







6/22
75
51
80
51
80
55
6/23
63
53
68
49
67
50
6/24
55
43
60
44
65
43
6/25
65
39
68
42
70
44
6/26
74
40
76
39
73
40
6/27
79
43
79
49
73
47
6/28
67
57
67
59
76
58
6/29
77
48
76
57
72
57
6/30
70
51
71
54
74
53
7/1
71
48
75
50
79
49
7/2
74
44
74
44
77
52
7/3
79
51
82
51
82
52
7/4
91
62
93
60
93
61
7/5
86
53
89
62
95
67







# Days Tmax>85
2
-
2
-
2
-
# Days Tmin>60
-
1
-
2
-
2


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