Soybean Sentinel Plot Report: August 4, 2026

This week, we have reports from extension educators from seventeen fields in ten counties. Their reports cover fields from growth stage R2 to R5. Our reports continue to reflect low insect and slug populations and low disease populations in the soybean fields that we are scouting. 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 some other pests like brown marmorated stink bugs and silver-spotted skipper caterpillars were found. Downy mildew, forgeye leafspot, powdery mildew, and Septoria brown spot were the 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

3 August 2026 – Beaver County – Stephen Campbell

Field near Fombell

Growth Stage: R3

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Deer – Severity: 4

3 August 2026 – Butler County – Stephen Campbell

Three fields: one near Marwood, one near Saxonburg, one near North Washington

Growth Stage: R3

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Septoria brown spot – Severity: 1
• Deer – Severity: 1 to 3

3 August 2026 – Indiana County – Stephen Campbell

Field near Brush Valley

Growth Stage: R2

• Grasshopper – Severity: 1
• Green stink bug – Severity: 1
• Japanese beetle – Severity: 1
• Septoria brown spot – Severity: 1
• Deer – Severity: 1

3 August 2026 – Lancaster County – Heidi Reed / Brooke Coble, Helen Sleat

Three fields: one near Collins, one near Elizabethtown, one near Willow Street

Growth Stage: R3-R4

• Bean leaf beetle – Severity: 1
• Blister beetle– Severity: 1 
• Brown marmorated bug – Severity: 1
• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Silver-spotted skipper – Severity: 1
• Soybean looper – Severity: 1
• Downy mildew – Severity: 1

31 July 2026 – Jefferson County – JohnMark Miller

Two fields: One near Sykesville, one near Troutville

Growth Stage: R3

• Japanese beetle – Severity: 1 to 2
• Cercospora leaf spot – Severity: 1
• Downy mildew – Severity: 4
• Deer – Severity: 1
• Flooding damage – Severity: 2

31 July 2026 – Cambria County – JohnMark Miller

Field near Patton

Growth Stage: R3

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 2
• Mexican bean beetle – Severity: 1
• Frogeye leafspot – Severity: 1
• Flooding damage – Severity: 2

31 July 2026 – Columbia County – Anna Hodgson

Field near Mainville

Growth Stage: R5

• Bean leaf beetle – Severity: 1
• Blister beetle Severity: 1
• Grasshopper – Severity: 1
• Green cloverworm caterpillar – Severity: 1
• Japanese beetle – Severity: 1
• Silver-spotted skipper caterpillar – Severity: 1
• Frogeye leafspot – Severity: 1
• Septoria brown spot – Severity: 1

31 July 2026 – Centre County – Adriana Murillo-Williams

Field near State College

Growth Stage: R4

• Japanese beetle – Severity: 1
• Downy mildew – Severity: 1
• Septoria brown spot – Severity: 1

30 July 2026 – Perry County – Ashley Isaacson

Field near Blain

Growth Stage: R3

• Bean leaf beetle – Severity: 1
• Brown marmorated stink bug – Severity: 1
• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Powdery mildew – Severity: 1 

30 July 2026 – Lebanon County – 

Del Voight / Brooke Coble, Helen Sleat

Three fields: one near Lebanon, one near Annville, one near Bordnersville

Growth Stage: R3-R4

• Bean leaf beetle – Severity: 1
• Grasshoppers – Severity: 1
• Japanese beetle – Severity: 1
• Deer – Severity: 1 to 6
• Powdery mildew – Severity: 1