Greenbug Expert System and Glance N Go Sampling for Cereal Aphids: Results of Field Testing

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Greenbug Expert System and Glance N Go
Sampling for Cereal Aphids Results of Field
Testing
Tom A. Royer Department of Entomology Plant
Pathology
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What is the Cereal Aphid Pest Management Expert
System?

• A computer program located at http//entoplp.oksta
  te.edu/gbweb/index.htm
• Developed by USDA ARS, SST Development Group and
  OSU.
• It has several elements
• Information on cereal aphids (UPDATED July 2005)
• A calculator for determining economic thresholds
  for greenbug infestations.
• A natural enemy module (UPDATED July 2005)
• A pesticide information module. (UPDATED July
  2005)
• A set of sampling plans for each economic
  threshold (UPDATED June 2004)

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Objectives for Developing Greenbug Expert System
In Winter Wheat

• Establish a treatment threshold based upon
  accurate Economic Injury Levels (EILs) for cereal
  aphids in different wheat production systems
  (dual purpose, grain only, forage?).
• Create a simple, accurate sampling strategy that
  reflects differences in aphid distribution
  patterns, crop susceptibility and natural enemy
  activity (Glance n Go).
• Develop an educational tool with information on
  natural enemies, pesticide selection and aphid
  biology.
• Develop a flexible system that could be expanded
  as additional information became available and/or
  interface with real-time weather data.

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Why Is This System Needed?

• Past recommendations for managing greenbugs were
  not determined from research-based damage
  relationships for grain or forage yield.
• No recommendations on managing BCOA.
• Consideration of natural enemy activity was
  rudimentary
• No consideration of production system (grain vs.
  dual purpose vs. forage).

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How Were These Tools Developed?

• Greenbug Treatment Thresholds based on an
  Economic Injury Level and a temperature-based
  greenbug development rate (Kindler et al 2003).
• Aphid Mummy decision tool built into system Giles
  et al 2004).
• BCOA Research in progress, but will soon be
  incorporated into new recommendations

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What is a Treatment Threshold (also known as an
Economic Threshold)

• A Treatment Threshold is based upon an existing
  Economic Injury Level (Kindler et al. 2003) and a
  sampling method (Giles et al 2000) that can
  effectively estimate pest numbers in a
  time-efficient manner.

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Using an Economic Injury Level

• Economic Injury Levels account for
• Cost of control
• Value of commodity
• Yield loss/pest unit
• Loss prevented by control

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A Treatment Threshold or Economic Threshold (ET)
is a Decision Tool
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A Treatment Threshold or Economic Threshold (ET)
is a Decision Tool
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What Does the Greenbug Expert System Provide?

• It is capable of using weather data to calculate
  treatment thresholds based upon the time of year

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What Does the Greenbug Expert System Provide?

• It allows a producer to play the what If game
  with pesticide costs, market values

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What Does the Greenbug Expert System Provide?

• It has a full complement of treatment threshold
  forms that can be printed off to serve as a
  permanent record of the sampling results

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What Does the Greenbug Expert System Provide?
Aphid Biology

• It has other educational modules that can be used

Natural Enemies
Insecticide Selector
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What Does the Greenbug Expert System Provide?

• It is readily adaptable to new results once they
  become available.

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What is Glance n Go Sampling ?

• Presence/Absence Sampling A sampling plan that
  estimates greenbug numbers without actually
  counting them, by counting infested tillers
  (GLANCE).
• Sequential Sampling
• Allows you to make treatment decisions On The
  GO You take only as many samples as needed to
  make a decision. Some fields may require only a
  very few samples, so you can move on to the next
  field.

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Sampling for Aphids in WheatPast Guidelines for
Greenbug

• Wait for evidence of injury (yellow spots etc in
  field)
• Examine 1 foot of row in at least 5 locations per
  field
• Avoid field edges
• Take more samples in fields greater than 80 acres

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Development of Glance n Go for Greenbugs

• Developed Glance n Go sampling plan, with
  statistical probabilities using 100 fields in
  Oklahoma.
• Actively sought input from from County Extension
  Educators, and crop consultants to make it as
  usable as possible.
• We are administering a tool to try and measure
  impact and adoption of this method over 3-5 years.

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How does Glance n Go Sampling for Greenbugs
Work?

• Examine 15 - 90 individual tillers, collecting 3
  samples per stop

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How does Glance n Go Sampling for Greenbugs
Work?

• Record counts of infested tillers, i.e. that have
  one or more greenbugs on a Glance n Go form,
  which is based on the time of year, and the
  pre-determined economic threshold.

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How does Glance n Go Sampling for Greenbugs
Work?

• Example of a Decision to Treat

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How does Glance n Go Sampling for Greenbugs
Work?

• Example of a Decision to Not Treat.

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How does Glance n Go Sampling for Greenbugs
Work?

• Example of a Decision to Not Treat.

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How does Glance n Go Sampling for Greenbugs
Work?

• Example of a No-Decision

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Why Does the Time of Year matter for Glance n
Go Sampling ?

• Patterns of infestation vary from year to year.
• Fall infestations normally occur from
  colonization of winged adults
• Spring infestations often develop from
  overwintering aphids that were already in the
  wheat field

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Greenbug Distribution Patterns in Winter Wheat in
Oklahoma
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Greenbug Distribution Patterns in Winter Wheat in
Oklahoma
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Why Doesnt the Size of the Wheat Plant matter
for Glance n Go Sampling ?

• AFTER the wheat reaches the 4 leaf stage, our
  research showed that greenbugs reduced yield in a
  consistent manner, regardless of the size of the
  plant.

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New Promises?

• Build in assessment of Bird cherry oat aphid into
  decision system.
• Develop similar system for Russian wheat aphid.
• Understand the economics of forage reductions by
  fall aphid infestations.

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Team Approach to Cereal Aphid Management

• USDA-ARS Laboratory Scientists
• Dr. Norm Elliott -Biological control, Area-wide
  management
• Dr. Dean Kindler-Host range, developmental
  biology
• Dr. Dave Porter - Host plant Resistance
• OSU
• Dr. Kristopher Giles - Biological control,
  integrated management of cereal aphids
• Dr. Eugene Krenzer - Wheat production
• Dr. Robert Hunger - BYDV management
• Dr. Tom Peeper - Chemical weed control.

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Greenbug Expert System and Glance N Go
Sampling for Cereal Aphids in Winter Wheat
Tom A. Royer Department of Entomology Plant
Pathology