Written by Robert Orpet, Washington State University, January 31, 2024.
Pre-bloom management of pear psylla is very important to reduce the potential size of subsequent generations. Pre-bloom is also a key time to manage some other pests like mites, scales, and mealybugs.
Drawing on lessons from previous projects in Washington (Alway 2001) and Oregon (VanBuskirk et al. 2002) in addition to current data (Orpet 2023), this article presents an integrated spray program that, over the long term, is intended to lower costs and fruit downgrades by promoting biocontrol of pests.
There are three pre-bloom spray timings (Table 1). Pear orchards on hillsides with late snow may miss the dormant timing. If so, this can be converted into a two-spray program starting with the delayed dormant spray applied as soon as it is safe.
Table 1
A basic pre-bloom spray program for pear insects and mites.
| Timing | Pear psylla behavior | Basic program materials |
|---|---|---|
| Dormant | Adults not active or just beginning activity | Particle film + oil for pear psylla |
| Delayed dormant | Adult immigration mostly complete, main period of egg-laying begins once green tissues emerge | Particle film + oil for pear psylla; pyriproxyfen for pear psylla; oil, lime sulfur for scales and rust mites |
| Popcorn | Eggs are starting to hatch into nymphs. | Pyriproxyfen for pear psylla; buprofezin for mealybug if needed |
Explanation of Materials
Particle films include kaolin clay (Surround CF or Surround WP) or diatomaceous earth (Celite 610). Pear psylla adults prefer not to settle on or lay eggs on treated surfaces (Nottingham et al. 2020) so these materials are best applied before eggs are laid.
Oil is also a deterrent of pear psylla oviposition. Like a particle film, dormant oil is most effective when sprayed before eggs are present (Zwick and Westigard 1978).
Lime sulfur has a minor effect on pear psylla and is very effective against scales and rust mites during delayed dormant (Westigard and Zwick 1972).
Pyriproxyfen causes the offspring of exposed adults to die during the egg stage or just after hatching (Higbee et al. 1995). Pyriproxyfen applications do not reduce adult or egg numbers but will reduce nymphs when applied before they hatch. Cluster bud is a more effective timing than delayed dormant (Dunley et al. 2001a,b). Esteem 35WP is a common pyriproxyfen product; two sprays are legal per year, at least 14 days apart, and no later than petal fall on the pear psylla label.
Buprofezin is another insect growth regulator. It is effective against grape mealybug (Dunley et al. 2001c) and has some effect on pear psylla nymphs (Dunley et al. 2002). Applications are probably only needed if the orchard already has a high mealybug population, as mealybugs tend to naturally decrease over time orchards practicing integrated pest management (Alway 2001).
Additional materials can be considered. Azadirachtin and cinnamon oil can suppress pear psylla (Nottingham et al. 2019, Nottingham and Sater 2021). However, harsher broad-spectrum pesticides like tolfenpyrad, novaluron, acetamiprid, and malathion are not included in this integrated pest management program. These chemicals provide little if any benefit when added on top of a kaolin-based program (Nottingham et al. 2022) and seem to be unneeded for long-term pear psylla control (VanBuskirk et al. 2002, Orpet 2023). Pre-bloom timings of pesticides reduce risk of harming beneficial insects, but some important spredators like Deraeocoris bugs overwinter in pear orchards (Westigard 1973) and could be killed. Therefore, it is suggested in this program to limit broad-spectrum materials to at most one pre-bloom and only if justified by large pear psylla populations.
Looking Ahead
After bloom, season-long integrated management guidelines for pear can be found online. A simple summary is in Table 2.
Table 2
A basic list of biocontrol-compatible management options for pear pests post-bloom.
| Pest | Basic program materials |
|---|---|
| Pear psylla | Rinsing off honeydew with overhead washing, summer pruning, particle films (Surround WP, diatomaceous earth), oil, spirotetramat, azadirachtin, cinnamon oil |
| Codling moth | Pheromone mating disruption, oil, virus, chlorantraniliprole, methoxyfenozide, pyriproxyfen |
| Pest mites | Fenbutatin-oxide, spirodiclofen, cyflumetofen, hexythiazox |
Like the pre-bloom program, broad-spectrum pesticides are not included. Pear psylla may cause damage during the first year of transitioning to this integrated program, but buildup of biocontrol control agents are expected reduce pear psylla damage in future years (Alway 2001, VanBuskirk et al. 2002, Orpet 2023). Once biocontrol communities are stable and pear psylla is low, limited use of some broad-spectrums may be used, when justified, without necessarily flaring pear psylla (Alway 2001, Amarasekare and Shearer 2017).
More Resources
- Follow along with the program’s evaluation during 2024. The Pear Insects Laboratory has been testing the integrated management guidelines in the Wenatchee Valley since 2022.
- Sign up to follow along with weekly scouting updates evaluating the program during 2024 with this link, or e-mail orpet@wsu.edu
- See previous years’ results.
- Free earwigs. If you are in the first or second year of trying an integrated or organic management program, your orchard may benefit from earwig inoculation. Learn more on the Earwig Transportation Workshop website. If you are interested in receiving free earwigs to release into your orchard to eat pear psylla, then e-mail orpet@wsu.edu to get on the list for a Wenatchee, Yakima, or Hood River region visit.
References
Alway, T. 2001. The Wenatchee Valley Pear IPM Project, 1999–2001: lessons from soft pest management programs. Report to Washington Tree Fruit Research Commission.
Dunley, J, B Greenfield, G Tannig, and H Bennett. 2001a. Control of pear psylla with diflubenzuron, and pyriproxyfen, 2000. Arthropod Management Tests.
Dunley, J, B Greenfield, G Tannig, and H Bennett. 2001b. Control of pear psylla with diflubenzuron, esfenvalerate, and pyriproxyfen, 2000. Arthropod Management Tests.
Dunley, J, B Greenfield, and L Bennett. 2001c. Control of grape mealybug, 2001. Arthropod Management Tests.
Dunley, J, B Greenfield, and L Bennett. 2002. Seasonal control of pear psylla, 2001. Arthropod Management Tests.
Higbee, B, D Horton, and J Krysan. 1995. Reduction of egg hatch in pear psylla (Homoptera: Psyllidae) after contact by adults with insect growth regulators. Journal of Economic Entomology 88: 1420–1424.
Nottingham, L, R Orpet, B Greenfield, and E Beers. 2019. Chemical control of pear psylla in pear, 2018. Arthropod Management Tests 44.
Nottingham, L, R Orpet, and E Beers. 2020. Greenhouse test on repellents of winterform pear psylla. Arthropod Management Tests 45:tsaa079.
Nottingham, L, and C Sater. 2021. Laboratory bioassay of organic insecticides on pear psylla, 2020. Arthropod Management Tests 46.
Nottingham, L, R Orpet, and E Beers. 2022. Integrated pest management programs for pear psylla Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), using kaolin clay and reflective plastic mulch. Journal of Economic Entomology 115:1607–1619.
Orpet, R. 2023. Year 2 of pheno-IPM for pear psylla management: it worked, 2023. Washington State University Tree Fruit, Comprehensive Tree Fruit site.
Shearer, P, and K Amarasekare. 2017. Stability of Cacopsylla pyricola (Hemiptera: Psyllidae) populations in Pacific Northwest pear orchards managed with long-term mating disruption for Cydia pomonella (Lepidoptera: Tortricidae). Insects 8.
VanBuskirk, P, R Hilton, and P Westigard. 2002. Five Years of Mating Disruption in Combination With Narrow-Range Petroleum Spray Oil To Control Pear Pest in Southern Oregon. Acta Horticulturae 596: 501–505. URL:
Westigard, P. 1973. The biology of and effect of pesticide on Deraeocoris brevis piceatus (Heteroptera: Miridae). The Canadian Entomologist. 105:1105–1111.
Contact
Dr. Robert Orpet
Washington State University
robert.orpet@wsu.edu
Funding and Acknowledgements
Funding for the project “Assessing and supporting effective areawide pear pest management” was provided by the Fresh Pear & Processed Pear Committees.
Fruit Matters articles may only be republished with prior author permission © Washington State University. Reprint articles with permission must include: Originally published by Washington State Tree Fruit Extension Fruit Matters at treefruit.wsu.edu and a link to the original article.
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