University of Minnesota Extension
www.extension.umn.edu
612-624-1222
Menu Menu

Extension > Minnesota Crop News > July 2016

Thursday, July 28, 2016

Japanese beetle populations increasing in soybean in parts of southeastern Minnesota


by Robert Koch (Extension Entomologist)

Japanese beetle, an invasive pest from Asia, is making its presence known. These large beetles with shiny green- and copper-colored bodies can be found feeding on many plants, including soybean, in agricultural areas that are in proximity to the Twin Cities, Rochester, and other urban areas in southeastern Minnesota. This beetle is not yet widely distributed in the state and is not likely to be in fields outside of these areas in southeastern Minnesota.


Thursday, July 21, 2016

Just the facts (Part 5): A review of the biology and economics behind insecticide recommendations

University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Nebraska: Robert Wright & Thomas E. Hunt
University of Wisconsin: Bryan Jensen
University of Illinois: Kelley Estes & Joseph Spencer

Biology helps determine the profitability of crop production on your farm – Ignoring biology is expensive


None of what we have presented here is new, or groundbreaking information. However, all of what we have presented here is based on science that has been vetted and implemented over thousands of acres for more than a decade. Economic injury levels take commodity prices, labor and control costs into account. Fortunately, the biological components of an EIL are not sensitive to commodity or input prices. The insects on your farm do not eat faster or more when crop prices are high or insecticide costs are low; nor is your crop more sensitive to insect damage (remember the damage boundary). Yield loss occurs at the same level of pest population, regardless of market prices of commodities. It makes no sense to treat if there is no reasonable likelihood of damage.

Wednesday, July 20, 2016

Just the facts (Part 4): A review of the biology and economics behind insecticide recommendations

University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Nebraska: Robert Wright & Thomas E. Hunt
University of Wisconsin: Bryan Jensen
University of Illinois: Kelley Estes & Joseph Spencer

Costs of treating soybean aphids too early


While some newer insecticides target a narrower range of insects, most insecticide applications are not specific. They will kill beneficial insects (lady beetles, parasitic wasps, etc.) as well as pests, later allowing soybean aphid populations to rebound in fields without those beneficial insects to slow them down. By using the ET, natural enemies will have a chance to suppress the aphid population and possibly prevent it from reaching economically damaging levels. After application, insecticide residues will kill insects for a short time, but insecticide activity invariably declines over time (generally, this is considered a good thing). With most insecticides registered for soybean aphid control (such as pyrethroids), soybean foliage emerging after treatment is not protected. Insecticides that are absorbed and translocated within soybean plants typically move upward only a leaf or two and eventually leave unprotected foliage, especially when applied early in the season.

Tuesday, July 19, 2016

Just the facts (Part 3): A review of the biology and economics behind insecticide recommendations

University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Nebraska: Robert Wright & Thomas E. Hunt
University of Wisconsin: Bryan Jensen
University of Illinois: Kelley Estes & Joseph Spencer

Economics of soybean aphid infestations: Math and biology matter


insect-population-effect-on-yield
Figure 1. Relationship of insect population and crop yield (Modified from Pedigo et al. 1986).
The lowest level of aphid infestation that has been shown to cause yield loss in soybean is several thousand aphid-days. This value, referred to as the damage boundary, is a biological relationship between the insect, crop, and environment, and is independent of crop and input costs. Below the damage boundary, no damage can be measured. Therefore, management efforts directed at treating aphid levels well below the damage boundary cannot provide a return on investment.

Monday, July 18, 2016

Just the facts (Part 2): A review of the biology and economics behind soybean aphid insecticide recommendations

University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Illinois: Kelley Estes & Joseph Spencer

How can soybean aphids reduce soybean yield?


The soybean aphid feeds on the phloem fluids (sometimes referred to as "sap") by inserting piercing-sucking mouthparts directly into the phloem vessels that carry products of photosynthesis from the leaves to other parts of the plant. Prior to feeding, aphids "taste" the sap to determine if the plant is a suitable host species and if the quality is acceptable. Once they settle and begin feeding, the injury from soybean aphid infestations can reduce plant growth, pod number, seed number, seed weight and seed oil concentration (2, 24). Early and prolonged aphid infestations can affect all yield components, while later infestations tend to only reduce seed size (2). In addition, soybean aphids decrease photosynthesis rates of soybean plants (11).

Hot weather during corn pollination

by Jeff Coulter, Extension Corn Specialist

Tassels recently became visible in many corn fields across Minnesota. This week a large percentage of the corn in Minnesota will be pollinating. Although air temperatures and soil moisture levels have been near optimal for corn in many areas of this region, hot weather is forecast for the second half of this week.

Sunday, July 17, 2016

Just the facts: A review of the biology and economics behind soybean aphid recommendations


University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Nebraska: Robert Wright & Thomas E. Hunt
University of Wisconsin: Bryan Jensen
University of Illinois: Kelley Estes & Joseph Spencer

Before soybean aphid was identified as a pest of soybean in the U.S. in 2000, insecticide applications to northern soybean crops were rare, targeting sporadic insect and mite outbreaks. Although large infestations have been relatively uncommon since the early to mid-2000’s, the soybean aphid is unquestionably still the key insect pest of soybeans in many North Central states. A tremendous amount of research and observational data has been obtained for this pest since its introduction and we have the tools and the knowledge to manage this pest effectively.

Friday, July 15, 2016

Initial forecasts of corn yield available for the Corn Belt

By Jeff Coulter, Extension Corn Specialist

Corn has begun silking in many fields across Minnesota. Stress to corn between now and early August resulting from dry soil conditions, especially when combined with high air temperatures, can decrease yield by reducing the number of kernels per plant. Hail damage to corn at this time also can seriously diminish yield, since all leaves have emerged by the onset of silking. Corn typically reaches maturity 55 to 60 days after the start of silking.

Thursday, July 14, 2016

Testing common waterhemp for resistance to PPO- inhibiting herbicides

Jeffrey L. Gunsolus, Extension Agronomist / Weed Science

Waterhemp populations that were not effectively controlled by early summer postemergence applications of PPO-inhibiting herbicides may be resistant to the widely used PPO-inhibiting soybean herbicides such as Cobra (lactofen), Flexstar (fomesafen), Marvel (fluthiacet-methyl & fomesafen) and Ultra Blazer (acifluorfen).

Assessing herbicide resistance in the field can be challenging because other factors such as weather, weed height, antagonism with another herbicide in the tank or using the wrong adjuvant could all contribute to poor control. Now one must also consider the likelihood that the waterhemp population is resistant to the PPO class of herbicides (Site of Action Group 14).

Tuesday, July 12, 2016

The Value of Straw

As harvest is approaching quickly and margins continue to be thin you may be contemplating whether it is worthwhile to bail straw. To put a value on something, we generally look at the marketplace and let supply and demand determine the value of the goods in quest on. To determine the value of straw, we can look at some local or regional hay auctions like the Central Minnesota Hay Auction in Sauke Centre to get some idea what livestock producers are willing to pay. However, we could also look at it from a different angle. Opportunity costs are defined as the costs of using a resource based on what it could have earned if used for the next best alternative. 

Thursday, July 7, 2016

Recovery and management of corn and soybean following wind and hail damage

by Jeff Coulter and Seth Naeve, Extension Agronomists

hail-damaged-corn-july7
Photo 1. Hail-damaged corn in Kandiyohi County, July 6, 2016. Source: Shannon Hauge
Strong winds and hail recently damaged many corn and soybean fields across Minnesota. Most corn was in the mid- to late vegetative stages (V11-V15) and within one to two weeks of tassel emergence when damaged, and soybean had 4-6 leaves and was well into the R1 stage. Damage included root lodging and stalk breakage from wind, along with leaf loss and stem bruising from hail.

Yield potential of hail-damaged crops depends largely on the remaining plant population, the type and severity of damage, and the growth stage when damaged. Information for evaluating recovery and management of damaged crops is available in:

Wednesday, July 6, 2016

Demonstrating the Extreme: Autotoxicity in Alfalfa

M. Scott Wells, David Nichol, and Roger Becker – UMN Forage Team

Autotoxicity is the chemical inhibition by a plant on the germination or growth of a plant of the same species, and has been suggested as one of the mechanisms for poor alfalfa emergence and growth. Although several factors influence autotoxicity such as soil texture, rainfall, and termination timing, research indicates a break in the production and/or crop rotation is needed avoid potential stand establishment problems. Typically, autotoxicity in alfalfa is not an issue, given the rotational schemes (e.g. corn following alfalfa). However there are growers that wish to renovate their current alfalfa fields, and commonly ask what are the impacts of doing so. Before we present the UMN Forage Teams recommendations concerning alfalfa autotoxicity, lets take this opportunity to show what happens in the most extreme settings.

Early Season Cover Crop Interseeding in Corn

M. Scott Wells, Alex Hard, Eric Ristau, and David Nicolai – UMN Cover Crop Team

mswells@umn.edu
http://z.umn.edu/forages

As many are aware, cover crops can provide growers with erosion control, reduce offsite movement of nutrients, support the development of soil organic matter, and in some cases provide additional revenue streams (e.g. forages, oilseeds). Even though cover crops offer several opportunities to growers who utilize them, historical, adoption has been marginal. It is estimated that less than 2% of the agricultural land in MN utilizes cover crops at some point in the rotation. There are several reasons for low adoption rates, but the most obvious reason is associated with the shorter growing season when compared to our neighbors in the South. The reduced growing season offers many challenges to successful integration of cover crops; however, there are new technologies that have the potential to overcome these challenges. The most notable technology involves early or late season cover crop interseeding (i.e. relaying cover crops into cash crops). Interseeding cover crops during the corn or soybean growing season can address some of the potential challenges (e.g. soil moisture and light) associated with shorter growing seasons. Currently the UMN Cover Crop team and Soil Health Partnership are researching innovative techniques, and equipment necessary to interseed cover crops in corn and soybean.

Tuesday, July 5, 2016

Register soon for the U of M Institute for Ag Professionals' Field School

by Dave Nicolai, Coordinator for Institute for Ag Professionals

The 2016 Field School for Ag Professionals will be held on July 26 - 27 at the University of Minnesota Agriculture Experiment Station, St. Paul Campus, University of Minnesota. The St. Paul campus, located in Falcon Heights, MN next to the Minnesota State Fairgrounds at Larpenteur and Gortner Ave, is this year's site for the 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. Register by July 20 in order to guarantee your participation!

'Shelly' wheat is newest University of Minnesota release

Shelley wheat
"Shelly" wheat is the newest variety from the University of Minnesota's hard red spring wheat breeding program.
"Shelly" is the newest wheat variety developed by the University of Minnesota and dates for touring demonstration plots have been announced. Released in January, 2016, Shelly is a high-yielding spring wheat variety well suited for much of the spring wheat-growing region.

In state trials it yielded equal to the popular varieties "Faller" and "Prosper," but with slightly better protein. The heading date of Shelly is similar to Faller. It possesses a good disease-resistance package with moderate resistance to scab, leaf rust and bacterial leaf streak. It also has an excellent rating for resistance to stripe and stem rust. Shelly is slightly shorter than Faller and has similar straw strength. It has good test weight and pre-harvest sprouting resistance.

June 2, 2016 Sauk Centre Hay Auction Summary


by Dan Martens, Extension Educator, Stearns-Benton-Morrison Counties, Crop Production, marte011@umn.edu, 3200-968-5077.

1. June 2 Summary by groups based on type, bale and quality.

2. History of Selected Lots through the auction season this year.

3. Graph of Selected Alfalfa hay groups.

June 2 graph drawn by hand, with number of loads noted. The Vertical line represents the range of values, High, Average, Low.

4. Summer Dairy Tour Flyer attached, including a note about our Central MN Forage Council summer forage tour/workshop.

I’d consider the hay markets kind of in a state of flux. Other sources of market information can be useful. A couple are listed below. Load numbers, variable quality, prices for other commodities and livestock produce can be factors. Consider some of these factors as you consider ranges and averages related to the hay you are looking for or aiming to sell.

Friday, July 1, 2016

White Heads

Jochum Wiersma, Madeleine Smith, and Phil Glogoza

It’s not the name of a band storming the Billboard charts but a simple description of partially or completely bleached wheat heads that stick out like a sore thumb in both spring and winter wheat this time of the year.  The following key will help you decipher the most likely cause of these white heads.
  • © Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy