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Soybean Sentinel Plot Program

Posted: August 31, 2016

As summer progresses and the soybean crop nears maturity insect issues become less consequential while other late-season yield robbers take center stage.

Most fields are approaching growth R6 when insect damage becomes less relevant, but in most cases insect and disease pressure remain mild. Grasshoppers and Japanese beetles are still the primary defoliators, but most populations remain below the economic threshold (15-20% defoliation). For fields with earlier stages of plants and strong populations of defoliators, the size of the beans and potential damage caused by driving over them need to be balanced with anticipated gains from any late-season insecticide applications. We expect these results to represent the majority of soybean fields in PA, but scout your fields to find out for yourself.

The Pennsylvania Soybean Promotion Board is funding a Soybean Sentinel Plot Program, which is being managed by Penn State Extension and The Dept. of Entomology at Penn State. In this effort, Penn State Extension Educators are regularly scouting 25 or so ‘typical’ soybean fields in nineteen counties across the state, reporting the populations of plant pathogens and insect pests that they find. Our goal is to keep folks aware of pests so that they will then scout their fields as part of an IPM program. It would be imprudent to use these reports as the basis or justification for an insecticide application or including insecticides in with a post emergence herbicide application.

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. Growers should be sure to check their own fields to determine your local populations, but these reports will give you a sense of what pests are active in fields. Our reports are distributed via this weekly newsletter, Penn State’s Field Crop News, and will be available in the next day or two on Penn State’s Field Crop Entomology website.

Weekly Reports

30 August - Elk County - Nicole Carutis

No-Till, Drilled
Growth Stage: R5

  • Japanese Beetle – Severity: 1
  • Aphids – Severity: 1
  • Grasshopper Nymphs – Severity: 1
  • Bean Leaf Beetle – Severity: 1
  • Soybean Thrips – Severity: 1
  • Frogeye Leaf Spot – Severity: 1

30 August – Lebanon County – Del Voight

Growth stage: R5

  • Bean leaf beetle – Severity: 1
  • Grasshoppers – Severity: 1
  • Brown leaf spot – Severity: 1

29 August – Mercer County – Gary W. Micsky

Growth stage: R6

  • Grasshopper – Severity: 1
  • Bean leaf beetle – Severity: 1
  • Thrips – Severity: 1
  • Japanese Beetle – Severity: 1
  • Green cloverworm – Severity: 1
  • Beneficial arthropods observed at low levels: Lady beetle adults and larvae and spiders
  • Slight brown spot on oldest leaves
  • 3 isolated spots showing slight bacterial blight and brown stem rot

29 August - Crawford County – Joel Hunter

Growth stage: R6

  • Japanese Beetle – Severity: 1
  • Bean Leaf Beetle – Severity: 1
  • (All insects are at very slight levels with defoliation well below 1%)
  • Slight Brown Spot – Severity: 1

29 August - Erie County – Joel Hunter

Growth stage: R5

  • Japanese Beetle – Severity: 1
  • Bean Leaf Beetle – Severity: 1
  • (All insects are at very slight levels with defoliation well below 1%)
  • Slight Brown Spot – Severity: 1

29 August - Bradford County – Mark Madden / Mason Tate

near Ulster, PA
Growth Stage R6

  • Japanese Beetle – Severity: 3
  • Grasshoppers – Severity: 4
  • No diseases noted

29 August - Potter County - Heather Supplee

Disked, Planted, 15 inch Rows, 2nd Year Beans
Growth Stage: R5

  • Japanese Beetle – Severity: 1
  • Green Stink Bug – Severity: 1
  • Grasshoppers – Severity: 1
  • No disease noted

29 August - McKean County - Heather Supplee

Disked, Planted, 15 inch Rows, 2nd Year Beans
Growth Stage: R5

  • Grasshoppers– Severity: 1
  • Bean Leaf Beetle - Severity 1
  • Frog Eye Leaf Spot- Severity 1
  • Bacterial Leaf Blight - Severity 1

29 August – Clinton County – Don Woodring

Near Mill Hall
Growth Stage: R5-6

  • Bean leaf beetles – Severity: 1
  • Grasshoppers – Severity: 3
  • Japanese beetles – Severity: 2
  • Green cloverworm – Severity: 3
  • Spotted Cucumber Beetle – Present at low levels
  • Brown Stinkbugs – Severity: 2
  • Aphids – Present at low levels
  • Lady Beetles – Present at low levels
  • Frog Eye Leaf Spot – Present at low levels

29 August – Clinton County – Don Woodring

Near Loganton
Growth Stage: R4-5

  • Bean leaf beetles – Severity: 1
  • Japanese beetles– Present at low levels
  • Grasshoppers – Severity: 1
  • Green cloverworm – Severity: 3
  • Spotted Cucumber Beetle – Present at low levels
  • Brown Stinkbugs – Severity: 2
  • Downy mildew – Present at low levels

29 August – Columbia County – Chris Houser/Joel Imgrund

Growth stage: R6

  • Bean Leaf Beetle – Severity: 1
  • Grasshoppers – Severity: 3
  • No diseases noted

29 August – Northumberland County – Chris Houser/Joel Imgrund

Growth stage: R6

  • Grasshoppers – Severity: 1
  • Cercospora - Severity: 1

29 August – Union County – Chris Houser/Joel Imgrund

Growth stage: R6

  • Grasshoppers – Severity: 2
  • Japanese beetles – Severity: 1
  • Aphids - Severity: 1
  • No diseases noted

Contact Information

John Tooker
  • Extension Specialist
Phone: 814-865-7082