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

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

2. 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: • 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) Oklahoma State University

3. 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. Oklahoma State University

4. 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). Oklahoma State University

5. 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” Oklahoma State University

6. 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. Oklahoma State University

7. Using an Economic Injury Level • Economic Injury Levels account for: • Cost of control • Value of commodity • Yield loss/pest unit • Loss prevented by control Oklahoma State University

8. Spray Decide A Treatment Threshold or Economic Threshold (ET) is a Decision Tool Oklahoma State University

9. Spray Decide A Treatment Threshold or Economic Threshold (ET) is a Decision Tool Oklahoma State University

10. What Does the Greenbug Expert System Provide? • It is capable of using weather data to calculate treatment thresholds based upon the time of year Oklahoma State University

11. What Does the Greenbug Expert System Provide? • It allows a producer to play the “what If” game with pesticide costs, market values Oklahoma State University

12. 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 Oklahoma State University

13. What Does the Greenbug Expert System Provide? • It has other educational modules that can be used: Aphid Biology Natural Enemies Insecticide Selector Oklahoma State University

14. What Does the Greenbug Expert System Provide? • It is readily adaptable to new results once they become available. Oklahoma State University

15. 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. Oklahoma State University

16. 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 Oklahoma State University

17. 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. Oklahoma State University

18. How does “Glance ‘n Go” Sampling for Greenbugs Work? • Examine 15 - 90 individual tillers, collecting 3 samples per stop Oklahoma State University

19. 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. Oklahoma State University

20. How does “Glance ‘n Go” Sampling for Greenbugs Work? • Example of a Decision to Treat Oklahoma State University

21. How does “Glance ‘n Go” Sampling for Greenbugs Work? • Example of a Decision to Not Treat. Oklahoma State University

22. How does “Glance ‘n Go” Sampling for Greenbugs Work? • Example of a Decision to Not Treat. Oklahoma State University

23. How does “Glance ‘n Go” Sampling for Greenbugs Work? • Example of a No-Decision Oklahoma State University

24. 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 Oklahoma State University

25. Spring Infestation 6 greenbugs/tiller Fall Infestation 6 greenbugs/tiller Greenbug Distribution Patterns in Winter Wheat in Oklahoma

26. Greenbug Distribution Patterns in Winter Wheat in Oklahoma

27. Why Doesn’t 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. Oklahoma State University

28. 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. Oklahoma State University

29. 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. Oklahoma State University

30. Greenbug Expert System and “Glance N’ Go” Sampling for Cereal Aphids in Winter Wheat Tom A. Royer Department of Entomology & Plant Pathology Oklahoma State University