Soybean Sentinel Plot Report: August 17, 2026
Crop scouts are finding silver-spotted skipper caterpillars in some soybeans fields. Photo credit: Penn State Extension.
Overview of reports from around Pennsylvania
This week, we have reports from extension educators from ten fields in five counties. Their reports cover fields from growth stage R3 to R6. Our scouting efforts continue to find low insect populations and few diseases in the soybean fields. As usual for this time of year, our reports identify bean leaf beetle, grasshoppers, and Japanese beetle as the main insect pests that are active, but we also found some other pests like soybean aphids, silver-spotted skipper caterpillars and three stink bug species. Septoria brown spot, downy mildew, and a few other diseases found. Unfortunately, deer continue to be active in some fields. Scout your own fields to learn what is active in your area. Good luck!
Background on the project
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
17 August 2026 – Lancaster County – Heidi Reed / Helen Sleat, Brooke Coble
Two fields: one Near Kirkwood, one near Willow Street
Growth Stage: R5
- Bean leaf beetle – Severity: 1
- Green stink bug – Severity: 1
- Japanese beetle – Severity: 1
- Brown marmorated stink bug – Severity: 1
- Brown stink bug – Severity: 1
- Soybean aphid – Severity: 1
- Silver spotted skipper caterpillar – Severity: 1
- Septoria brown spot – Severity: 1
- Soybean mosaic virus – Severity: 1
- White mold – Severity: 1
17 August 2026 – Dauphin County – Heidi Reed / Brooke Coble
Field near Bellaire
Growth Stage: R5
- Brown marmorated stink bug – Severity: 1
- Septoria brown spot – Severity: 1
- Sudden death syndrome – Severity: 1
17 August 2026 – Lancaster County – Heidi Reed / Helen Sleat, Brooke Coble
Field near Elizabethtown
Growth Stage: R5
- Grasshopper – Severity: 1
- Downy mildew – Severity: 1
- Soybean mosaic virus – Severity: 1
14 August 2026 – Centre County – Adriana Murillo-Williams
Field near State College
Growth Stage: R5
- Japanese beetle – Severity: 1
- Silver spotted skipper caterpillar – Severity: 1
- Septoria brown spot – Severity: 1
- White mold – Severity: 1
14 August 2026 – Cambria County – JohnMark Miller
Field near Patton
Growth Stage: R6
- Grasshopper – Severity: 1
- Mexican bean beetle – Severity: 1
12 August 2026 – Lebanon County – Del Voight / Brooke Coble, Helen Sleat
Three fields: one near Lebanon, one near Annville, one near Bordnersville
Growth Stage: R3-R5
- Bean leaf beetle – Severity: 1
- Grasshoppers – Severity: 1
- Green cloverworm – Severity: 1
- Green stink bug – Severity: 1
- Japanese beetle – Severity: 1
- Silver spotted skipper caterpillar – Severity: 1
- Soybean leafminer – Severity: 1
- Deer – Severity: 5
- Groundhog – Severity: 2
- Downy mildew – Severity: 1
- Septoria brown spot – Severity: 1-2
11 August 2026 – Lancaster County – Heidi Reed / Helen Sleat
Near Kirkwood
Growth Stage: R4-R5
- Grasshopper – Severity: 1
- Japanese beetle – Severity: 1
- Brown stink bug – Severity: 1
- No diseases noted
