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Showing posts from July, 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 commodi…

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 economic…

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 can be me…

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…

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 w…

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

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 To determine whether a corn plant will survive and regrow following damage, split stalks and exa…