Soybean Sentinel Plot Report: August 19, 2025

Overview of reports from around Pennsylvania

This week we have ten reports from ten counties, even though our regular scouting efforts were disrupted by Ag Progress Days. The fields we scouted are approaching maturity; they were in growth stages R4 and R5. Insect and pathogen populations remain low. The insects that we found are typical for this time of year and included Japanese beetle, grasshoppers, and green cloverworm, among others. Septoria brown spot and frogeye leaf spot were the most common diseases but their populations were mostly low, probably due to dry conditions. 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

18 August July 2025 – Centre County – Adriana Murillo-Williams

Field near Bellefonte
Growth stage: R5

• Bean lean beetle – Severity: 1
• Japanese beetle – Severity: 1
• Green cloverworm – Severity: 1
• Grasshoppers – Severity: 1
• Brown marmorated stink bug – Severity: 1
• Silver spotted skipper – Severity: 1
• White-tailed deer – Severity: 1
• Downy mildew – Severity: 1
• Frogeye leaf spot – Severity: 1
• Soybean vein necrosis – Severity: 1

18 August 2025 – Butler County – Stephen Campbell

Field near Saxonburg
Growth Stage: R5

• Grasshoppers – Severity: 1
• Japanese beetles – Severity: 1
• White-tailed deer – Severity: 2
• Beneficial species present: lady beetles, spiders
• Downy mildew – Severity: 1
• Septoria brown spot – Severity: 2

18 August 2025 – Perry County – Ashely Issacson

Field near Duncannon
Growth Stage: R5

• Bean lean beetle – Severity: 1
• Japanese beetle – Severity: 1
• Green cloverworm – Severity: 1
• Grasshoppers – Severity: 1
• Green stink bug – Severity: 1
• White-tailed deer – Severity: 2
• Beneficial species present: lady beetles, spiders
• Septoria brown spot – Severity: 1
• Cercospora leaf blight – Severity: 1

18 August 2025 – Beaver County – Stephen Campbell

Field near Fombell
Growth Stage: R5

• Soybean aphid – Severity: 2
• Grasshoppers – Severity: 1
• Japanese beetle – Severity: 1
• White-tailed deer – Severity: 2
• Beneficial species present: fireflies, lady beetles
• Septoria brown spot – Severity: 1

 15 August 2025 – Mercer County – Erin Cuprinka

Field near Mercer
Growth Stage: R4

• Grasshoppers – Severity: 1
• Beneficial species present: bumble bee, fireflies, spiders
• Septoria brown spot – Severity: 1

14 August 2025 – Somerset County – Leanna Duppstadt

Field near Berlin
Growth Stage: R4

• Green cloverworm – Severity: 1
• Grasshoppers – Severity: 1
• Beneficial species present: hover flies, spiders
• Septoria brown spot – Severity: 1
• Downy mildew – Severity: 1
• White mold – Severity: 1 

13 August 2025 – Bradford County – Casey Guindon

Field near Columbia Cross Roads
Growth Stage: R4

• Japanese beetle – Severity: 1
• White-tailed deer – Severity: 3
• Beneficial species present: lady beetles
• Septoria brown spot – Severity: 1
• Frogeye leaf spot – Severity: 1
• Cercospora leaf blight – Severity: 1

12 August 2025 – Lebanon County – Del Voight/Tyler McFeaters

Field near Cornwall
Growth Stage: R5

• Japanese beetle – Severity: 1
• Silver-spotted skipper – Severity: 1
• No diseases noted 

11 August 2025 – Franklin County – Tosh Mazzone

Field near Mercersburg
Growth stage: R4

• Japanese beetle – Severity: 1
• Green cloverworm – Severity: 1
• Grasshopperw – Severity: 1
• Groundhog damage – Severity: 1
• Beneficial arthropods: hover flies, lady beetles, spine soldier bugs
• Frogeye leaf spot – Severity: 1

11 August 2025 – Lancaster County – Jeff Graybill

Field near Manheim
Growth stage: R5

• Japanese beetle – Severity: 1
• Grasshoppers – Severity: 1
• Septoria brown spot: Severity: 4