Oklahoma State University Greenbug Expert System and “Glance ‘N Go” Sampling for Cereal Aphids: Results of Field Testing Tom A. Royer Department of Entomology

Oklahoma State University

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

Tom A. Royer

Department of

Entomology&

Plant Pathology


What is the Cereal Aphid Pest Management Expert System? A computer program located at

http://entoplp.okstate.edu/gbweb/index.htm Developed by USDA ARS, SST Development Group

and OSU. It has several elements:

1. Information on cereal aphids (UPDATED July 2005)

2. A calculator for determining economic thresholds for greenbug infestations.

3. A natural enemy module (UPDATED July 2005)

4. A pesticide information module. (UPDATED July 2005)

5. A set of sampling plans for each economic threshold (UPDATED June 2004)


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.


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).


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”


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.


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


What Does the Greenbug Expert System Provide? It is capable

of using weather data to calculate treatment thresholds based upon the time of year


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

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



It has other educational modules that can be used:

Aphid Biology

Insecticide Selector

Natural Enemies



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



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.


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


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.


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

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.



Example of a Decision to Treat



Example of a Decision to Not Treat.



Example of a Decision to Not Treat.



Example of a No-Decision



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

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


Greenbug Distribution Patterns in Winter Wheat in Oklahoma

Fall Infestation

6 greenbugs/tiller

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Greenbug Distribution Patterns in Winter Wheat in Oklahoma


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.

Why Doesn’t the Size of the Wheat Plant matter for “Glance ‘n Go” Sampling ?


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.


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.


Greenbug Expert System and “Glance N’ Go” Sampling for Cereal Aphids in Winter Wheat

Tom A. Royer

Department of

Entomology&

Plant Pathology

Documents

Oklahoma State University Greenbug Expert System and “Glance ‘N Go” Sampling for Cereal Aphids: Results of Field Testing Tom A. Royer Department of Entomology