Soybean Sentinel Plot Report: August 16, 2022

Summary of reports:

The reports this week indicate that insect pest populations remain mostly low. Grasshopper, Japanese beetle, and bean leaf beetle populations are most evident, but only in some areas are populations large enough to be concerning. While not reflected in our scouting reports this week, anecdotally Mexican bean beetle populations appear more widespread this season, which is notable if trend continues. Typically, they have been limited to southern York and Lancaster Counties, where they are perennial visitors to some fields. I would be interesting in hearing if you encountered Mexican bean beetle this year more than usual. As always, you cannot assume that your fields have economically significant pest populations; scout your fields to determine if populations are approaching economic threshold. Once soybeans reach R4 and beyond, the economic threshold for insect defoliation is 30% defoliation across an entire field, so damage needs to be pretty significant to justify an insecticide application that would require driving over part of the crop.

For diseases, dry weather continues to limit most pathogens, but our scouts are finding that some fields have low populations of downy mildew, Septoria, or white mold. Again, scout your fields to determine what they may harbor! For information on 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

15 August 2022 – Lancaster County – Jeff Graybill

Near Manheim

Growth stage: R5

• Grasshopper – Severity: 3
• Septoria brown spot – Severity: 2
• Drought Stress – Severity: 6

15 August 2022 – Centre County – Adriana Murillo-Williams

Field between Bellefonte and State College

Growth stage: R5

• Bean leaf beetle – Severity: 1
• Grasshopper – Severity: 1
• Soybean leaf miner – Severity: 1
• Downy mildew – Severity: 1
• White mold– Severity: 1

15 August 2022 – Somerset County – Leanna Dupptstadt

Field near Somerset

Growth stage: R4

• Japanese beetle – Severity: 1
• Bean leaf beetle – Severity: 1
• Downy mildew – Severity: 1

15 August 2022 – Montgomery County – Andrew Frankenfield

Near Souderton

Growth stage: R1

• Grasshopper beetle – Severity: 2
• Bacterial blight – Severity: 2
• Septoria brown spot – Severity: 2

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

Two fields, one north of Saxonburg, one south of Saxonburg

Growth stage: R3 (South), R4 (North)

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Soybean aphid – Severity: 1 (North)
• Sudden death syndrome – Severity: 1 (South)

15 August 2022 – Bedford County – Leanna Dupptstadt

Field near Fishertown

Growth stage: R5

• Japanese beetle – Severity: 1
• Bean leaf beetle – Severity: 1
• No diseases of note

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

Near Independence

Growth stage: R6

• Grasshopper – Severity: 1
• Japanese beetle – Severity: 1
• Green cloverworm – Severity: 1
• Brown marmorated stink bug – Severity: 1
• Green stink bug – Severity: 1
• Sudden death syndrome – Severity: 1
• Deer damage evident