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Showing posts from 2016

New pictorial guide aids in Palmer amaranth and tall waterhemp identification

by Phyllis Bongard and Jeff Gunsolus With the recent confirmation of Palmer amaranth in Minnesota, it is critical to identify this noxious weed, so it can be eradicated before it becomes widespread. A new pictorial guide compares key characteristics of Palmer amaranth and tall waterhemp at several growth stages throughout the growing season to aid in this identification.

Palmer Amaranth in MN: Reporting, preventing further infestation and monitoring

Jeff Gunsolus, Extension Agronomist - Weed Science Photo 1. Palmer amaranth plant from Yellow Medicine County, MN. Photo: Bruce Potter Following yesterday’s confirmation of the presence of Palmer Amaranth (Amaranthus palmeri) in Yellow Medicine County, University of Minnesota Extension and the Minnesota Department of Agriculture (MDA) sent out a joint news release describing where this plant was detected, photos to assist in identification, the biological reasons why this weed is on the MDA’s Prohibited – Eradicate Noxious Weed list and why efforts to eradicate this weed are critical to Minnesota’s commodity crop producers.

Check pollinator plantings for Palmer amaranth

Jeff Gunsolus, Bruce Potter and Roger Becker Photo 1. Suspected Palmer amaranth plant from Yellow Medicine County, MN. Photo: Bruce Potter Although we are waiting for final confirmation, we strongly advise people to check their pollinator planting sites for the presence of Palmer Amaranth. Yesterday Bruce Potter followed up on a crop consultant's request to investigate a newly established pollinator planting in Yellow Medicine County. The grower and consultant are to be commended for detecting and reporting this site during the establishment year.

Brown marmorated stink bug detected in Minnesota soybean

by Robert Koch (Extension Entomologist) and Daniela Pezzini (Graduate Student) The brown marmorated stink bug (BMSB) was recently detected for the first time in Minnesota soybean. A single adult specimen was collected in sweep net samples from a soybean field in Dakota County on August 17, 2016. Follow-up sampling of that same field performed on August 25, 2016 did not detect any additional BMSB. This invasive pest of Asian origin uses piercing-sucking mouth parts to feed on developing soybean pods and seeds. In more easterly states, this insect has caused significant yield losses to soybean and other crops. In Minnesota, we are unaware of any fields with densities of stink bugs near treatable levels; therefore, we do not envision any insecticide treatments being needed for this pest at this time. The intent of this article is to alert you to the presence of this new invader, which could become a threat to Minnesota crops in the near future. Further information on BMSB and other sti

Palmer amaranth: A new weed threat to watch out for

Lisa Behnken, Fritz Breitenbach, Jeff Gunsolus, Phyllis Bongard, Liz Stahl Photo 1 . Palmer amaranth in a Tennessee field. Source: Lisa Behnken Palmer amaranth is not native to the northern US, but has spread northward from southern states, being confirmed in Wisconsin, Iowa, Illinois and Nebraska (2011–2013), South Dakota (2014) and other northern states. In 2016, it was discovered in newly-seeded CRP land in Iowa, including Clayton County, just one county away from southeastern Minnesota.

Two miticides recently received registration for use against twospotted spider mites in soybean

by Robert Koch (Extension Entomologist) and Bruce Potter (IPM Specialist) Growers now have access to two more miticides for use against twospotted spider mites in soybean. These miticides are Agri-Mek SC (Syngenta) and Zeal SC (Valent). These are welcomed additions to the limited suite of chemicals for management of twospotted spider mites in soybean.  They represent insecticide groups (modes of action) not used for soybean aphid.

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 co

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 econ

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 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

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 conce

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

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).

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

by Jeff Coulter and Seth Naeve, Extension Agronomists 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: Corn Damage and Replant Guide: https://extension.umn.edu/corn-planting/corn-crop-damage-and-replant-options Soybean Damage and Replant Guide: https://extension.umn.edu/soybean-planting/soybean-damage-and-replanting Corn Recovery

Do foliar fungicides provide a benefit to corn damaged by hail?

by Dean Malvick, Extension Plant Pathologist Hail damage has recently occurred to corn in Minnesota that was primarily at the V7-9 growth stage. Some producers are asking about the value of applying foliar fungicides to corn damaged by hail. This article will cover key points on this topic and summarize results from field studies.

Stay on top of giant ragweed

Lisa Behnken, Extension Educator, Fritz Breitenbach, IPM Specialist SE Minnesota, Jeff Gunsolus, Extension Agronomist, Weed Science, and Phyllis Bongard, Content Development and Communications Specialist, University of Minnesota Photo 1. Giant ragweed in corn herbicide trial at Rochester, MN, May 20,2016. Plot was planted April 25, 2016. The recent frost across southeast Minnesota may have slowed down corn and soybean development, but it did not slow down the rate of weed growth. There are plenty of 1-4 inch giant ragweed and 1-2 inch common lambsquarters in corn and soybean fields. Waterhemp is also beginning to emerge (1/4 – 3/4 inch). The current dilemma that needs to be addressed is most evident in fields where a preemergence herbicide was not used or it provided poor giant ragweed control. In addition, our recent 1-2 inch rainfall may limit the ability to get into the field in a timely manner to control the weeds when they are most susceptible to control and before they

Laundering Pesticide-Contaminated Clothing

By Lizabeth Stahl, Extension Educator – Crops, and Dean Herzfeld, Pesticide Safety Education Coordinator A question raised at several Private Pesticide Applicator workshops this year was how to best handle pesticide-contaminated clothing. Although waterproof suits and aprons are key pieces of personal protective equipment (PPE) to wear when handling, mixing, loading, or applying pesticides, conventional work clothing is the primary label-required PPE for many products. Proper handling of pesticide-contaminated clothing can minimize pesticide residues in the home and avoid human exposure.

Potential impact of cold temperatures on herbicide-induced crop injury and effective weed control

Jeff Gunsolus, Extension Agronomist - Weed science Last week’s cold and wet conditions followed by the weekend’s frost creates the potential for herbicide-induced crop injury from soil- and post- applied herbicides as well as reduced postemergence weed control. Postemergence applications The warmer and dryer conditions projected for this week are encouraging for crop recovery. Therefore it is wise to allow for a few days of warm weather for the crops and weeds to recover before heading out to the field to apply any postemergence herbicide. Your crops need time to recover so they can adequately metabolize the herbicide, thus preventing herbicide-induced crop injury and the weeds will need time to recover before they can take up the herbicide and move the herbicide to active growing sites.

The Three Biggies: Urea, Anhydrous Ammonia, and UAN

Fabián G. Fernández Nitrogen (N) fertilizer is extremely important for crop production. There are many sources available in the marketplace, but the three most important in order of tonnage sales for Minnesota are urea, anhydrous ammonia, and urea ammonium nitrate (UAN). Since many are very busy applying N and doing other field operations at this time, my purpose is not to go into a lengthy discussion on N sources but I thought it would be good to review a few important points.   

Manage waterhemp in soybean with layered residual herbicides

Lisa Behnken, Extension Educator, Fritz Breitenbach, IPM Specialist SE Minnesota, Jeff Gunsolus, Extension Agronomist, Weed Science, and Phyllis Bongard, Content Development and Communications Specialist, University of Minnesota With waterhemp becoming more widespread and herbicide resistant populations expanding, including multiple-resistant populations, waterhemp is increasingly difficult to manage. In addition, it has a long emergence pattern and frequently outlasts control of an early preemergence herbicide application. One strategy is to layer residual herbicides to control glyphosate-resistant waterhemp by extending the duration of seedling control.