Written by Ricardo Lima Pinto, Tianna DuPont, WSU Extension. January 2, 2024. Updated February 2, 2025
Washington State University is piloting a Scouting Network to provide pear growers with natural enemy and pest information. Scouting is an essential tool for integrated pest management (IPM) which integrates cultural and biological as well as insecticidal controls, and employs monitoring and economic thresholds. After the second year of the pilot participants reported using scouting data to improving fruit quality and facilitating adoption of IPM.
What is the Scouting Network?
The goal of the Scouting Network is to provide pear growers with weekly pest and natural enemy information to support effective implementation of pear pest management. Participants receive weekly scouting information including psylla adults and natural enemies per beat tray; psylla nymphs, mites and mealy bugs per leaf; and projected psylla populations. The scouting report is available by mobile app, e-mail and text messages (Figure 1,2).
Why have a Scouting Network?
Intensive scouting of natural enemies as well as pests is critical in order to effectively apply new bio-based integrated pest management (bIPM) tools to improve fruit quality and reduce broad spectrum sprays. Growers and consultants asked us to develop new tools because standard psylla spray programs are costing $1000 to $1800 but not always providing consistent results (e.g. US#1 packouts from standard programs ranging from 62 to 99%)1. The IPM toolbox now has new tools: phenology timings, economic and natural enemy thresholds, products which conserve natural enemies and is providing similar fruit quality on average to standard programs2. However, more boots on the ground from scouts is critical to apply IPM. We “need a lot of eyes in the orchards to do IPM,” consultants explain. Scouting for IPM which includes natural enemies can take twice the time. “If I did not have this scouting data, I would only be able to do IPM on a few blocks,” another participating consultant explained. Scouting Network information on natural enemy populations can allow growers to avoid late season sprays when predator populations are high and psylla numbers are low. “We were able to stop spraying earlier when we saw natural enemies come in,” one participant explained.
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1Fruit graded for pear psylla honeydew damage in 2018 and 2019 (DuPont et al. 2021a).
2Fruit quality in IPM has been similar to standard on avg with $173 fewer costs (DuPont and Strohm 2020).
How do we scout?
We use a standardized method of beat trays and leaf samples collected randomly in the orchard so numbers can be compared to thresholds. Scouts take 30 beat trays randomly zig-zagging along transects which cover the variation in the entire 10 to 20 acre pear block. Each tray consists of 3 firm taps with a stiff rubber hose on a 0.75 to 1.5 inch-diameter limb 3 to 6 feet off the ground over a 18-in square tray with white cloth. In summer scouts select 100 leaves per block (10 from each of 10 randomly selected trees) for leaf brush counts. We make sure to select 5 leaves from the lower canopy with 2 in the tree center and 3 in the middle of each of 2 scaffold limbs per tree. We use a telescopic pruner to collect 5 leaves from 2 shoots or clusters that are difficult to spray such as the upper canopy and the back side of limbs. Many samples (e.g. 30 trays) and sampling which targets both areas likely to have high psylla numbers (e.g. tree centers and tops), as well as across the tree, allow us to compare overall populations and compare to thresholds developed with the same methods.
What did growers and crop consultants find useful about the Scouting Network?
The Scouting Network is informing spray decisions resulting in reduced psylla, better fruit quality and reduced spray costs. We surveyed the 12 growers and 8 consultants 2023 project participants using interviews and online surveys. Participant growers told us they are using the scouting information to inform their spray decisions (77%, 570 acres), improving spray timing and effectiveness (62%, 404 acres), improving fruit quality (50%, 356 acres), and facilitating adoption of IPM (54%, 340 acres). Consultants said they used Scouting Network information to inform spray decisions (88%, 1486 acres). In some cases, consultants were able to reduce late season spray recommendations by 2-3 sprays (50% on 1358 acres). Scouting is an essential tool for the IPM program. Participants told us that the “scouting data helped me know if IPM was working,” and “having the scouting network is a safety to feel comfortable using IPM.”
In the second year the Scouting Network expanded to 87 registered blocks with a total of 914 acres and 45 participants. Six scouts were involved in the project including two WSU grant funded scouts and one chemical distributor sponsored, one packing house, and two grower paid scouts. 15 orchardists managing 1095 acres and five consultants recommendations for 2424 acres participated in the year wrap up survey to tell us how things were going. 85% of orchardists and consultants participants reported making changes to their pest management programs as a result of the project. Growers reported using scouting network information to inform their spray decisions (87%, 859 acres), reducing one to three spray applications (67%, 525 acres), maintaining selective programs with biocontrol (soft, IPM; 73%, 969 acres). As a result of these changes orchardists reported the scouting network facilitated the adoption of IPM practices (67%), increased natural enemies on the farm (47%), and moderate or significant reductions in pesticide expenses (53%). 2024 Scouting Network participants said, “I transitioned 200 acres to IPM. We had less psylla at the end of the season, fruit was clean, trees looked healthier with fewer inputs.” “We used the data to decide where to start sprays and to target insect growth regulators.” “Overall [scouting data] gave me the confidence to spray less harmful products as natural enemies were present and my spray bill was lower.” “It feels like there are 3 sets of eyes, the degree day model, the scouts and the consultants. That is invaluable. It allows us to dial in our timing.”
How can I join the network?
Let us know if you have interest in having plots that you would like to be scouted in the 2025 season. If you have staff that wants to be trained in how to scout, we can provide both training and access to the scouting network platform which will send you weekly reports. Scouting Network data will be most useful for blocks transitioning to IPM which use selective materials and where you hope to see natural enemies. It can also be useful for problem blocks. Currently the Scouting Network is in the Wenatchee River Valley, and we are working with Rebecca Schmidt Jeffris, USDA-ARS to expand to Yakima area, and Chris Adams to pilot in the Hood River Oregon area.
Funding and acknowledgements
The scouting network project was funded by the Washington State Specialty Crop Block Grant (2023 to 2024). Current funding includes USDA Crop Protection Grant: Implementing New Tools for Pear Integrated Pest Management.
A huge thank you to Ricardo Lima Pinto for development of the Scouting App and management of the project in 2023 and 2024.
This work was supported by the participants farmers and managers: Dave Burnett, Rollin Smith, Glade Brosi, Evelyn Arnold, Erica Bland, Keith and Kathy Archibald, Wayne Reiman, Kevin Carney, Loren Baird, Mel Weythman, Jorge Zavola, Blaine Smith, Sam Parker, Matt McDevitt, Shawn Cox and field staff: Scott Cummings, Neil Johnson, Troy Davis (Chamberlin Ag.) Kevin Kenoyer, Randy Nelson, Keith Granger (Wilbur-Ellis) Chuck Weaver, Jake Carson (GS Long) and Chris Strohm (NWW).
Additional information
Pear psylla integrated pest management
Contacts
Tianna DuPont
WSU Extension
tianna.dupont@wsu.edu
(509) 713-5346
References
DuPont, S. T. and C. J. Strohm (2020). “Integrated pest management programmes increase natural enemies of pear psylla in Central Washington pear orchards.” Journal of Applied Entomology 144(1-2): 109-122.
DuPont, S. T., Strohm, C., Kogan, C., Hilton, R., Nottingham, L., & Orpet, R. (2023). Pear psylla and natural enemy thresholds for successful integrated pest management in pears. Journal of Economic Entomology.
Nottingham, L. and E. H. Beers (2022). Improving pear pest management with integrated approaches. Wenatchee, WA, Washington State Tree Fruit Research Commission. Final Report.
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