Written by Molly Sayles and Robert Orpet, Washington State University, November 7, 2024.
In 2024, WSU’s Pear Entomology Lab conducted the third year of sampling Wenatchee Valley orchards following phenology-based integrated pest management (Pheno-IPM) guidelines and nearby paired conventional orchards. The Pheno-IPM guidelines use a degree-day model to predict pear psylla life stages, thereby improving the timing of cultural tactics and selective sprays. Instead of broad-spectrum insecticides, Pheno-IPM relies on biological control to suppress pear psylla. The Pheno-IPM guidelines are provided online. A July 2023 article lists examples of products used in conventional and IPM sites during the summer of last year.
Pest damage and materials cost
On average over the three years of sampling, pear psylla damage was similar between Pheno-IPM and conventional orchards, with conventional having 1% less damage (Table 1). The Pheno-IPM orchards experience damage in June (Fig. 1), when biological control has yet to establish robust populations, whereas conventional orchards experience damage near harvest time, when lack of biocontrol allows pear psylla to flare. In 2022 and 2023, conventional management cost $300 more per acre in insecticides and miticides than Pheno-IPM. Overall, we can conclude that on average, over the past three years, IPM orchards had similar damage to conventional orchards and was less expensive.
Post-harvest populations
Pear psylla adults increased in August in conventional orchards and are currently 10 times the populations of pear psylla in Pheno-IPM orchards. This pattern, seen also in 2022 and 2023, is as expected, because conventional orchards lack the biological control needed to suppress psylla after sprays conclude. High pear psylla populations produced in conventional orchards may contribute to next season’s pressure in spring.
If you are interested in trying pear IPM, take a look at the phenology-based guidelines. For year-long insect monitoring data encompassing Wenatchee, Hood River, and Yakima, timely management guidelines, and upcoming events subscribe to Pear Entomology Weekly email newsletter.
Table 1. Honeydew damage from pear psylla represented by percentage of Anjou downgrades and materials cost. Downgrade numbers are based on what WSU entomologists learned at a local packinghouse and subsequently observed at commercial orchards using conventional (N = 6) or IPM (N = 6) spray programs in the Wenatchee Valley.
| Year | Anjou downgrade | Materials cost/acre | ||
|---|---|---|---|---|
| IPM | Conv. | IPM | Conv. | |
| 2022 | 11% | 8,0% | $1,140 | $1,425 |
| 2023 | .05% | 4.2% | $998 | $1,390 |
| 2024 | 23% | 16% | TBD | TBD |
| AVG | 11.5% | 9.3% | $1,070 | $1,400 |
Fig. 1. Pear psylla adults at orchards using conventional (N=7) and IPM (N=9) throughout the Wenatchee Valley in 2024. This figure includes more sites than the damage/cost table above.
More resources
- Learn about pear psylla management: https://treefruit.wsu.edu/crop-protection/opm/pear-psylla/
- See previous years’ damage results in the November 2023 issue of Tree Fruit Matters.
- Sign up to follow along with weekly scouting updates evaluating the program during 2024 with this link, e-mail orpet@wsu.edu
Contact
Dr. Robert Orpet
Washington State University
Molly Sayles, PhD Candidate
Washington State University
Funding and acknowledgments
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.
