Soybean Sentinel Plot Report-7 August 2018

With the extremely wet weather, insect pests in soybeans appear to have been knocked back a bit. Diseases remain low, but this could change with more moisture.
Soybean Sentinel Plot Report-7 August 2018 - News

Updated: August 8, 2018

Soybean Sentinel Plot Report-7 August 2018

A spined soldier bug eating a lady beetle larva. Predators are key to keep soybean populations from getting too high. Predator-on-predator predation is bound to happen when aphid populations grow & predators swarm in. Adriana Murillo-Williams

Our reports this week from 13 counties across Pennsylvania counties indicate that populations of insects and pathogens continue to be low in soybean fields. The large amounts of rain that we received last week appear to have limited insect pest populations with Japanese beetle and grasshopper populations now appearing to be lower. Soybean aphids are more widely distributed this week. Remember that aphid populations tend to be very spotty and unpredictable. Their economic threshold is 250 aphids per plant across an entire field. Lady beetles and other predators can do a great job limiting their populations, so if you have a lot of aphids but strong populations of predators, be cautious about applying insecticides because the predators may solve the problem for you for free! When it comes to soybean aphid and many pests of soybeans, they are unlikely to affect yield beyond growth stage V5-6.

For pathogens, Septoria brown spot continues to be the most commonly reported disease, but some fields contain soybean vein necrosis virus, frog-eye leaf spot, and downy mildew. Despite the rain, we have no reports of white mold. Scout your fields to understand local populations.

This growing season, the Pennsylvania Soybean Promotion Board is funding a Soybean Sentinel Plot Program, which is being managed by The Dept. of Entomology at Penn State and executed by Penn State Extension. In this effort, Penn State Extension Educators are regularly scouting 25 or so ‘typical’ soybean fields in twenty counties across the state, reporting the populations of plant pathogens and insect pests that they find. Our goal is to inform folks which pests are active across the state, so that they 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.

7 August – Bedford County – Zach Larson

Growth stage: V5

  • Green cloverworm – Severity: 1
  • Japanese beetle – Severity: 2
  • Lady beetles abundant
  • Septoria Brown Spot – Severity: 1

7 August – Dauphin County – Liz Bosak

Growth stage: R2

  • Grasshoppers – Severity: 1
  • Japanese beetles – Severity: 1
  • No diseases noted

6 August – Bradford County – Casey Guindon

Growth stage: R4

  • Grasshoppers – Severity: 1
  • Green cloverworm – Severity: 1
  • Soybean aphid – Severity: 1
  • Lady beetles abundant
  • No diseases noted

6 August – Cambria County – Zach Larson

Growth stage: V4

  • Bean leaf beetle – Severity: 1
  • Green cloverworm – Severity: 1
  • Japanese beetle – Severity: 1
  • Lady beetles abundant
  • Septoria Brown Spot – Severity: 3

6 August – Crawford County – Joel Hunter

Growth stage: R2-R3

  • Japanese beetle – Severity: 1
  • Grasshoppers – Severity: 1
  • Bean leaf beetle – Severity: 1
  • Soybean aphid – Severity: 1
  • Septoria Brown Spot – Severity: 1

6 August – Lancaster County - Jeff Graybill

Two fields
Growth Stage – R4-R5

  • Grasshoppers – Severity: 1
  • Green cloverworm – Severity: 1
  • Japanese beetle – Severity: 1
  • Bean Leaf Beetle – Severity: 1
  • Septoria Brown Spot – Severity: 2

6 August – McKean County – Nicole Carutis

Growth stage: R2

  • Lady beetles abundant
  • Septoria Brown Spot – Severity: 4

6 August – Northumberland County – Anna Busch

Growth stage: R5

  • Bean leaf beetle – Severity: 3
  • Grasshoppers – Severity: 1
  • Japanese beetle – Severity: 1
  • Soybean aphid – Severity: 1
  • Lady beetles present
  • Soybean vein necrosis virus – Severity: 1

6 August – Lebanon County – Del Voight

Four fields, all with similar populations
Growth stage: R3-R4

  • Bean leaf beetle – Severity: 1
  • Grasshoppers – Severity: 1
  • Green cloverworm – Severity: 1
  • Japanese beetle – Severity: 1
  • Septoria brown spot – Severity: 1
  • Soybean vein necrosis virus – Severity: 1
  • Soybean downy mildew – Severity: 1

6 August – Union County – Anna Busch

Growth stage: R2

  • Bean leaf beetle – Severity: 1
  • Green cloverworm – Severity: 1
  • Soybean aphid – Severity: 1
  • Lady beetles present
  • No diseases noted

6 August – Potter County – Nicole Carutis

Two fields
Growth stage: R2 – R3

  • Lady beetles present
  • No diseases noted

3 August – Centre County – Adriana Murillo-Williams

Growth stage: R2

  • Brown marmorated stink bug – Severity: 1
  • Grasshoppers – Severity: 1
  • Japanese beetle – Severity: 2
  • Soybean aphid – Severity: 3
  • Lady beetles abundant
  • Soybean downy mildew – Severity: 3
  • Frog-eye leaf spot – Severity: 1

Authors

Insect ecology Plant-insect interactions Conservation biological control Chemical ecology Gall insects

More by John Tooker, Ph.D.