Integrated Management of Whiteflies in Arizona

1. Integrated Management of Whiteflies in Arizona Peter C. Ellsworth, Ph.D. IPM Specialist, University of Arizona Maricopa, AZ, USA & Steve Naranjo, Ph.D. Research Scientist, USDA-ARS, WCRL Phoenix, AZ, USA

2. Arizona World Distribution of Outbreaks of B. tabaci

3. State of Arizona, U.S.A. Maricopa Agricultural Center (~350 m) Majority of cotton production in AZ Yuma Agricultural Center (~50 m)

4. Impact of SWF on Arizona • Whiteflies (biotype B) invaded Arizona in the early 1990s. • Losses to the agricultural industry were catastrophic. • Honeydew excreted by SWF caused sticky cotton that could not be sold at a premium price after outbreaks in 1992 & 1995.

5. AZ Lint Lost Value • In the late 1980s, AZ enjoyed a premium for its cotton lint relative to New York Futures. • The 1992 & 1995 outbreaks led to depressed prices for AZ lint, a loss that we continue to endure in spite of clean cotton. 0¢

6. Pest Trends in Arizona (1990-2000) • The 1995 outbreak led to a 25-yr high in foliar insecticide use in cotton. • There was a major shift in insecticide use in 1996...

7. IGRs, Bt cotton, & AZ IPM Plan introduced Arizona IPM Plan Introduced • …due to the introduction of insect growth regulators, Bt cotton, and the Arizona IPM plan. • 1999 was a 25-yr low in foliar insecticide use in cotton.

8. Whitefly IPM… …depends on 3 basic keys 3 2 1

9. Avoidance …all practices that serve to prevent or maintain pests below economic levels. 1

10. Crop Management …some factors lead to increased SWF numbers, such as water-stress, excess N, or hairy-leafed cultivars

11. Exploitation of Pest Biology & Ecology …knowing your “enemy” will help guide prevention efforts, such as specific information on how SWFs are dying & the role of natural enemies

12. Area-Wide Impact …is needed for this mobile & polyphagous pest & includes elements of cooperation, source reduction & attention to SWF movement...

13. Areawide Impact …also depends on stable systems of management to be in place for all sensitive crops in order to reduce area-wide pressure.

14. When SWF are damaging... …we depend on the top two levels of the pyramid 3 2 1

15. Sampling …sits atop the pyramid & serves all layers of management.

16. Sampling (~ 7 min. / field) • Locate 5th leaf (below terminal) • Score as infested with adults when… 3 or more adults present • Examine quarter-sized leaf disk • Score as infested with nymph when… 1 or more LARGE nymphs present • Tally up 30 leaves & 30 leaf disks

17. Locate between main veins Count adults first “Quarter-sized” disk 5th leaf Large nymphs Presence / Absence count on 30 leaves Field Sampling for Nymphs Determine % infested

18. Action Thresholds …with sampling, can be used to precisely time sprays with IGRs (Stage I) & other insecticides (Stage II & III).

19. Whitefly Thresholds • Timing of IGRs (Stage I) 40% of leaves infested with 3 or more adults 40% of disks infested with 1 or more large nymphs • Timing Stage II & III conventional sprays 57% of leaves infested with 3 or more adults

20. Selective & Effective Chemistry …the insect growth regulators sit at the center of our pyramid.

21. Major Points of Insect Growth Regulation pyriproxyfen Knack ® Knack ® Adult 4th, Egg “pupa” Crawler 2nd 3rd Applaud ™ Applaud ™ buprofezin

22. IGRs & Natural Enemy Conservation …demonstrate the interaction between levels of the pyramid to produce “bioresidual”...

23. What is “Bioresidual”? biological Overall killing power of an insect control technology including the direct effects of the technology (i.e., chemical residual) PLUS the associated natural biological mortality. Ellsworth & Martinez-Carrillo, 2001 insectice

24. UTC chemical residual chemical residual UTC IGRs v. Conventional Chemistry Bioresidual via natural mortality extends the effectiveness of IGRs, while conventional sprays kill natural enemies & require repeated sprays. … 4 conventional sprays vs. just 1 IGR spray in 1997. … commercial-scale studies are shown for two years here... One IGR spray lasts ONLY 14 days chemically … 3 conventional sprays, or just 1 IGR spray needed in 1999. 1999 1997 7–8 weeks bioresidual bioresidual ~6 weeks threshold

25. Recommended Strategy 1) Use IGRs first (1 use each only) 40% infested leaves AND 40% infested disks 2) Use IGRs without mixing with other chemicals (if possible) don’t waste the bioresidual 3) Delay the use of follow-up sprays for 14–21 days i.e., at least 1 generation of whiteflies

26. Resistance Management …is a shared responsibility to ensure efficacy of our valuable chemistry. All chemistry falls into 1 of 3 stages...

27. Three Stage Strategy • Stage I: Use IGR of choice when counts exceed threshold • Follow-up with alternate IGR, if needed • Use each no more than once • Stage II: Use Stage II (non-pyrethroid) materials at least once before Stage III materials • Do not use foliar neonicotinoids in multi-crop communities or more than twice in cotton areas • Stage III: Reserve use of pyrethroid mixtures until end of season, and no more than twice

28. Conclusions (1) • With the adoption of the AZ IPM plan, SWF sprays have been reduced by 71% to around 1 spray per season, and growers have saved over $100 million in control costs and yield savings in the last 5 years. • The AZ IPM plan depends on multiple elements of “Sampling” & “Effective Chemical Use” built on a foundation of “Avoidance”.

29. Conclusions (2) • Six years of success have been based on research-based guidelines for sampling & thresholds, access to powerful & selective IGRs with proven guidelines for their use, the extended suppressive interval, known as “bioresidual”, which maximizes natural mortality factors of the SWF & creates area-wide benefits, and an organized & comprehensive educational campaign

30. Information ACIS • All University of Arizona crop production & crop protection information is available on our web site, • Arizona Crop Information Site (ACIS), at • http://ag.arizona.edu/crops