Gary Grove, Washington State University

1. The Care and Feeding of the Hop Powdery Mildew (PM) Fungicide Toolbox Photo courtesy of David Gent Gary Grove, Washington State University

2. The more full and diverse the fungicide toolbox, the more opportunity to keep it that way!

3. Hop Powdery Mildew (PM) Fungicide Toolbox

4. Fungicide Resistance Action Committee http://www.frac.org

5. Fungicide Resistance Action Committee http://www.frac.org

6. Fungicide Mode of Action • How a fungicide works or how it conducts its business • Inhibition of sterol biosynthesis • Inhibition of signal transduction • Respiratory inhibitors

11. Types of Resistance resistant sensitive QoI Flint Pristine DMI Procure Rally fenarimol compounds tebconazolecompounds Qualitative (sudden) QoI Quantitative (gradual/ rate dependent) DMI

12. Factors Affecting Fungicide Resistance • Fungicide use frequency • Fungicide use pattern • Epidemiological timing • Reproductive rate of pathogen • Rate of pathogen spread • Basic pathogen biology (i.e. sexual stage)* • Fungicide mode-of-action (multi-site versus single-site) • Application type & conditions What is our PM risk?

13. Photo courtesy David Gent • Extended control season • Multiple applications (~8) • Limited chemistries • Rapid reproductive rate

14. Fungicide Resistance Color Codes High Moderate Low

19. WA Hop PM Situation • Intensive fungicide programs • Rapidly reproducing pathogen • Pathogen is aerially dispersed • Main lines of defense are resistance-prone • Documented resistance of other PM’s to most main lines of defense • Fortunately no documented sexual stage (chasmothecia, cleistothecia, ascocarps) • Risk, particularly to QoI compounds, is HIGH

20. General Guidelines • The loss of any one first-line classes compromises the entire fungicide “toolbox” • Use cultural practices that lower disease pressure • REDUCE THE NUMBER OF SPRAYS • LIMIT POPULATION EXPOSURE • Always use fungicides in a protective, rather than reactive, manner: It is far easier to prevent powdery mildew than to cure it. • ******Know the trade name, chemical name, class, and FRAC resistance codes when designing a management program • Do not tank mix or alternate QoI fungicides with the same FRAC number in a spray program. • DMI’s can be alternated in a program provided that the number of seasonal or sequential applications is not exceed for the CLASS or FRAC Group* • Medium risk compounds such as DMI (Group 3) and quinoline compounds (Group 13) should be applied no more than 3 times per season and no more than twice in sequence. • High risk: no more than 2-3 times per year and no sequential usage (if possible)

21. Fungicide Choice Efficacy Cost Time Effect on beneficials Resistance Risk Limitations MRL issue’s Effect on mites Disease Management

22. Photo courtesy David Gent late bloom > cone development

23. Fungicide Resistance Color Codes High Moderate Low

24. Fungicide Class Color/Pattern Codes 11 11 QoI (strobilurins; Flint, Pristine) 3 SBI* (Rally, Procure, Folicur, +) 3 ………… ………… 13 Quinolines (Quintec) ………… ………… Sulfur, oil, biologicals * DMI and Amine compounds

25. Alternations 2 QoI Compounds 2 DMI Compounds Folicur Rally 3 3 11 11 Yes Rally Rally Folicur Pristine Flint 3 3 3 NO! NO! Time

26. Premixes and Tank Mixes for Resistance Management • Both active ingredients of premixes and tank mixes must be active against target organism at labeled concentrations • In some cases may control multiple diseases • Tank mixes must be separate modes of action / FRAC Groups (built in with premixes) Pristine pyraclostrobin Flint 11 11 boscalid Sulfur 7 M2 Tank Mix Premix

27. Tank Mixes 2 QoI Compounds 2 DMI Compounds 11 Rally Flint 3 3 11 Pristine Procure NO!

29. The more full and diverse the fungicide toolbox, the more opportunity to keep it that way!

30. PM Management Program Iterations* 2 Modes of action 3 Modes of action 4 Modes of action 1 = exceeds number of applications/season 2 = exceeds sequential applications/season

32. QoI (Group 11) Guidelines • Never exceed more than two QoI applications in sequence. If two sequential applications of a QoI fungicide are made, this “block” should be alternated with at least two applications of one or more fungicides of a different mode of action or FRAC group. • When Group 11 compounds are used as a solo product (Pristine), the number of applications should be no greater than 1/3 of the total number of fungicide applications per season. • In programs utilizing tank mixes or pre-mixes of a Group 11 fungicide with a fungicide of another group (e.g. Pristine), the number of Group 11 fungicide (QoI)-containing applications should be no more than 1/2 of the total number of fungicide applications per season.

34. Resistance Risk + Class

35. Premixes for Powdery Mildew* Adament* Pristine Unicorn* *Not registered for use on hops

37. 11 (QoI) 3 (DMI) 13 (Quin) 7 (Carb)

38. 11 3 3 11 7 3 M2

39. Fungicide Color and FRAC Codes Color = Resistance Risk High Moderate Low

40. Fungicide Color and FRAC Codes Number = Fungicide Class / FRAC Group = DMI fungicide, moderate risk 3 7 13 = quinoline fungicide, moderate risk = quinoline fungicide, moderate risk

41. Tank Mixes and Premixes Pristine Flint pyraclostrobin 11 11 boscalid Sulfur 7 M2 Premix Tank Mix

42. Know Your Products! 11 11 11 11 3 3 3 M2 M2 11 13 13 13 3 3 3

44. Premixes cyprodinil difenconazole Inspire Super*

45. pyraclostrobin QoI component Carboximide component boscalid Pristine

46. Pristine (Premix) QoI component pyraclostrobin = Carboximide component boscalid

47. QoI / QoI Premix Fungicides