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Showing posts from August, 2017

Field studies: What do you mean 5 bushels per acre is not significant?

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

Tillage plots at the Southwest Research and Outreach Center, Lamberton, MN. Photo: Liz Stahl Utilizing sound research results to help make decisions on the farm is a wise business practice. It can be confusing, however, when you see two numbers that are clearly not the same labeled as "not significantly different." One can quickly calculate the value of a few bushels per acre over hundreds of corn or soybean acres. It is key to look at just what this terminology means and its practical importance when using this information to make decisions.

Use small grain stubble fields to boost forage supply

By: Jared Goplen and Eric Mousel

Photo 1: Forage cover crops have the potential to reduce feed costs. Photo: Eric Mousel. Now is the prime time to be seeding small grain stubble fields with a cover crop to be grazed this fall, winter or next spring. One of the many benefits of incorporating small grains into the crop rotation is the ability to get a forage cover crop established by the end of August, which is a great way for beef and dairy producers to add value to their crop fields by extending the grazing window or adding to the forage supply.

Mow fenceline weeds now to prevent seed production

By: Jared Goplen and Dave Nicolai

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.

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.

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 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.

When good butterflies go bad

Bruce Potter, IPM specialist and Bob Koch, Extension entomologist

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

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. 

Infestations have been found in the areas around Crookston and westward toward East Grand Forks. 

We urge farmers to pay attention to lodged areas of fields to determine if sawfly are a contributing cause of the problem. While driving the combine, lodged stems should be visible from the cab (Figures 1 and 2). Infested stems are plugg…

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

by Jeff Gunsolus, Extension weed scientist

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

Late season weed escapes in soybeans? What Now?

By Jared Goplen, Dave Nicolai, Lisa Behnken, Jeff Gunsolus
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. Is there a herbicide available for rescue treatment? The short answer is no. Although it would be great to have a herbicide rescue treatment to control escaped waterhemp and other weed species that are now 3+ feet in height in soybean, there are no control options available. The crop stage at this point is generally advanced far enough that products, such as Roundup, Liberty, Flexstar, dicamba, and others are no longer labeled for use in soybean. Although some may be inclined to spray Cobra or other lactofen-conta…

Assessing and documenting yield loss due to dicamba injury in soybean

by Jeff Gunsolus, Extension weed scientist
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. Relationship of injury symptomology to yield Dicamba injury symptoms range from cupping and strapping of newly emerged leaves to height reduction and injury to growing points. Symptoms will reflect the level of exposure to dicamba. A publication written by Rodrigo Werle, Richard Proost and Chris Boerboom contains color photos of dicamba injury symptoms, mimics and assessment of yield loss:

Soybean injury from dicamba

Due to the challenges of associating dicamba injury symptoms to yield loss, the only equitable way that I can think…

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.