Soybean Sentinel Plot Report: August 2, 2022

Grasshoppers are feeding in soybean fields, but their damage is only approaching economic thresholds in some fields, so scout your fields to know their status. (Photo by Sarah Frame, Penn State Extension)

Summary of reports:

The reports this week indicate that pathogen populations remain low due to dry weather keeping many diseases in check. In some areas, however, Septoria brown spot is being found but only at low levels. For insect pests, populations remain mostly low. As mentioned last week, in some area grasshopper and Japanese beetle populations are creeping up to potentially concerning levels. Scout your fields to determine if populations are approaching economic threshold. While soybean pods are small and soft (through R3), the economic threshold for leaf defoliation is 15% across an entire field. Once pods start hardening, the economic threshold increases to 30% defoliation across an entire field. For more details on economic thresholds in soybeans and implementing IPM in soybean fields, see our recently published fact sheet on the topic.

Background

This growing season the Pennsylvania Soybean Promotion Board is funding a Soybean Sentinel Plot Program, which is being managed by The Department of Entomology at Penn State and executed by Penn State Extension. In this effort, Penn State Extension Educators are regularly scouting about 25 'typical' soybean fields in about 20 counties across the state, reporting the populations of plant pathogens and insect pests that they find. Our goal is to inform the agricultural community about which pests are active across the state, so folks will have a sense of what to expect when they scout their own fields as part of an IPM program. It would be inappropriate to use these reports to justify insecticide applications.

In the reports below, pests that were found during scouting are listed with their severity, which is rated on a 1-10 scale with 10 being the highest. A severity score of 1 equates to 10% or less infestation or defoliation, a "2" aligns with 20% or less infestation or defoliation, and so on. Growers should be sure to check their own fields to determine your local populations, but these reports will indicate which pests are likely to be active in fields. Our reports are distributed via this weekly newsletter and are available via the Penn State Extension website (then search for "soybean sentinel plot").

 Reports

1 August 2022 – Lancaster County – Jeff Graybill

Near Manheim

Growth stage: R5

• Grasshopper – Severity: 1
• Bean leaf beetle – Severity: 1
• Septoria brown spot – Severity: 1

1 August 2022 – Washington County – Leanna Dupptstadt / Adam Hohn

Near Independence

Growth stage: R3

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Green cloverworm – Severity: 2
• Green stink bug – Severity: 1
• Sudden death syndrome – Severity: 1
• Deer and groundhog damage evident

1 August 2022 – Somerset County – Leanna Dupptstadt

Field near Somerset

Growth stage: R2

• Japanese beetle – Severity: 1
• Green stink bug – Severity: 1
• Bean leaf beetle – Severity: 1
• Grasshopper – Severity: 1
• Green cloverworm – Severity: 1
• Redheaded flea beetles – Severity: 1
• Frogeye leaf spot – Severity: 1

1 August 2022 – Butler County – Justin Brackenrich / Adam Hohn

Near Saxonburg

Growth stage: R2

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Cercospora leaf blight – Severity: 1
• Deer and groundhog damage evident

1 August 2022 – Northumberland County – Anna Hodgson

Near Rushtown

Growth stage: R5

• Japanese beetle – Severity: 1
• Bean leaf beetle – Severity: 1
• Green cloverworm – Severity: 1
• Green stink bug – Severity: 1
• Silver-spotted skipper caterpillar – Severity: 1
• Potato leafhopper – Severity: 1
• Beneficial species evident: spined soldier bug
• Soybean vein necrosis – Severity: 1
• Septoria brown spot – Severity: 1

1 August 2022 – Montgomery County – Andrew Frankenfield

Near Souderton

Growth stage: R1

• Japanese beetle – Severity: 2
• Grasshopper – Severity: 2
• Septoria brown spot – Severity: 2
• Drought stress evident
• Herbicide injury evident – Severity: 3

1 August 2022 – Bedford County – Leanna Dupptstadt

Field near Fishertown

Growth stage: R3

• Japanese beetle – Severity: 1
• Bean leaf beetle – Severity: 1
• Green stink bug – Severity: 1
• Grasshopper – Severity: 1
• No diseases of note
• Beneficial arthropods present: spiders, spined soldier bug

27 July 2022 – Chester County – Sarah Frame

Near South Pottstown

Growth stage: R4

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Soybean thrips – Severity: 1
• Septoria brown spot – Severity: 1
• Downy mildew – Severity: 1
• Drought stress is evident

27 July 2022 – Berks County – Sarah Frame

Near Brownsville

Growth stage: R2

• Japanese beetle – Severity: 1
• Grasshopper – Severity: 1
• Soybean aphid – Severity: 1
• Beneficial arthropods present: minute pirate bugs
• Septoria brown spot – Severity: 1
• Deer damage evident