Table 1. Materials available for cherry powdery mildew control.
Excerpt from the WSU Crop Protection Guide. For timings at which each pesticide can be used refer to the Crop Protection Guide.
d = dormant; dd= delayed dormant; pp= prepink/pink; b = bloom; pb = post bloom; sf = shuck fall; es = early summer (14-32 after full bloom); s = summer; ls = late summer; ph = preharvest; h = harvest; ah = after harvest
The FRAC code represents the mode of action of the fungicide. Multiple applications of a fungicide(s) with the same FRAC code increases the risk that resistance will develop. Premix fungicides with two modes of action can improve disease control if there is field resistance to one of the active ingredients and help prevent resistance if there is not. Group 11 fungicides, important for cherry powdery mildew, are high risk for resistance development. It is important for resistance management to use cultural practices to reduce disease pressure. Apply fungicides in a protective rather than reactive manner. Limit the number of applications of a single mode of action both during the season and in sequence (rotate between colors, Figure 7). Apply medium risk compounds no more than three times per season and no more than twice in sequence. High risk compounds should always be alternated with other modes of action. Apply high risk compounds to no more than 30% of the total sprays you use in a single season. Tank mixing with sulfur (or other low risk compounds) can also help limit resistance risk.
- Cherry Powdery Mildew Questions and Answers, Gary Grove, Claudia Probst, Tianna DuPont, Dec 2017.
- Cherry powdery mildew: Expect the unexpected, Claudia Probst, Gary Grove, WSU video, January 2015.
- Cherry powdery mildew management guidelines, WSU-DAS article, web page, 2013.
- AgWeatherNet, model status & recommendations for Cherry powdery mildew, web page.
- Mildew threatens cherries all season, M. Hansen, Good Fruit Grower, February 2015.
- WSU Cherry Powdery Mildew Information Network, Facebook.
- Fungicide Resistance Action Committee, web page.
- Rosaceae Nemesis: Cherry Powdery Mildew, RosBreed Newsletter, December 2016.
Calabro, Jill Marie, Robert A. Spotts, and Gary G. Grove. 2009. Effect of training system, rootstock, and cultivar on sweet cherry powdery mildew foliar infections.” HortScience 44.2: 481-482.
Glawe, Dean A. 2008. The powdery mildews: a review of the world’s most familiar (yet poorly known) plant pathogens. Annu. Rev. Phytopathol. 46: 27-51.
Grove, Gary G. 1998. Meteorological factors affecting airborne conidia concentrations and the latent period of Podosphaera clandestina on sweet cherry. Plant disease 82.7 (1998): 741-746.
Grove, Gary G., and Robin J. Boal. 1991a. Overwinter survival of Podosphaera clandestina in eastern Washington. Phytopathology 81.4: 385-391.
Grove, Gary G., and R. J. Boal. 1991b. Powdery mildew of sweet cherry: Influence of temperature and wetness duration on release and germination of ascospores of Podosphaera clandestina. Phytopathology 81.10: 1271-1275
Long, L. Cherry Powdery Mildew Control. Oregon State University Extension.
Ogawa, J.M., Zehr, E.I., Bird, G.W., Ritchie, D.F., Uriu, K., and Uyemoto, J.K. 1996. Compendium of Stone Fruit Diseases. St. Paul, MN: APS Press. ISBN: 978-0-89054-174-6.