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Reducing areawide pear psylla winterforms requires an areawide effort

Sticking the landing, post-harvest psylla populations

by Chris McCullough, Robert Orpet, Molly Sayles, and Louis Nottingham

November 7, 2022

  • During the 2022 pear growing season, our WSU pear entomology team monitored pear psylla and its natural enemies (predators and parasitoids) across orchards in the Wenatchee Valley.
  • Orchards were either conventional, organic, or followed our new phenology-based Integrated Pest Management (IPM) program (detailed in this link: All programs experienced highs and lows in terms of pear psylla.
  • Conventional had great control of pear psylla during summer. However, as harvest approached, the elimination of natural enemies resulted in pear psylla nymph populations dramatically increasing (Figure 1).
  • Meanwhile, in organic and IPM orchards, natural enemy populations increased and kept pear psylla nymph abundance lower than in conventional orchards (Figure 1).
  • These differing scenarios meant a tradeoff between early-season damage in IPM and organic orchards vs. a sticky harvest and the risk of late-season damage in conventional orchards.
  • We evaluated damage in the field, and pear psylla marking downgrades averaged out to be similar between IPM and conventional orchards.

Read the whole article on the WSU Tree Fruit site.

Figure 1: Summary graphs of the average number of pear psylla nymphs, adults, and natural enemies from the beginning of August until mid-October at fields that practiced conventional, IPM (“Pheno” = phenology-based IPM guidelines), and organic psylla management.

Codling moth study covers many questions, many miles

October 27, 2022

Sterilized codling moths are marked with colored powder (Ross Courtney/Good Fruit Grower)

The October 2022 issue of the Good Fruit Grower featured our ginormous codling moth project covering 45 sites across 6,500 square miles of Central Washington.  The project is led by Nottingham lab postdoc Rob Curtiss with assistance from research technician Toriani Kent.

In the past few years, a resurgence of codling moth concerns in the Northwest has launched a renaissance in the corresponding science. A Washington and Oregon task force held virtual summits throughout the spring and is now conducting surveys about management programs. The research commission put codling moth at the top of its priority list for 2022.

Growers hope Curtiss’ project yields clear recommendations regarding traps per acre, pest-density estimations and efficient combinations of disruption and lures.


IPM for Psylla Using Kaolin and Reflective Mulch

Integrated Pest Management Programs for Pear Psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), Using Kaolin Clay and Reflective Plastic Mulch

Reflective mulch plot

September 1, 2022

Pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), is the most economically important pest of pears grown in Washington State. Standard conventional management programs involve season-long broad-spectrum insecticide sprays. Although the industry uses some tools that are not disruptive to biological control, such as kaolin clay and selective insecticides, they are additions to broad-spectrum insecticides instead of replacements. Conventional sprays suppress pear psylla through the spring and early summer; however, disruption of biological control leads to pear psylla outbreaks near harvest. In 2018 and 2019, we tested two season-long programs that used only selective approaches. The programs began with either kaolin clay or reflective plastic mulch and were followed by identical spray programs using only selective insecticides. Programs were compared with an industry standard conventional program that used numerous broad-spectrum insecticides throughout the season, and a check program with no insecticides for pear psylla. Experiments were conducted using replicated 40-tree plots in a research orchard near Wenatchee, WA with high pear psylla pressure. In both years, selective programs had similar pear psylla densities to the industry standard program and all had lower pear psylla densities and fruit injury than the check. Both selective programs had lower fruit injury than the industry standard in the first year, and similar injury to the industry standard in the second year. Our results suggest kaolin clay and reflective mulch can effectively suppress pear psylla populations and injury in the early season and support season-long selective management programs without the use of broad-spectrum insecticides.

Early-Career Parenting: Surviving, If Not Thriving

June 10, 2022

Early-Career Parenting: Surviving, If Not Thriving

by Katlyn A Catron, PhD

This article was originally published in the Summer 2022 edition of “American Entomologist”

The early stage of an entomologist’s career is filled with difficult decisions: do I take a postdoc, an industry job, or just light my degrees on fire and become a bog witch? For many early-career professionals (ECPs), a major but infrequently discussed choice must be made during this same period—can my career survive a child right now?

I accepted a postdoc position in October of 2020, and a little over a month later found out that I was pregnant. I was ecstatic, but that joy was marred with uncertainty and nausea from more than just hormones. How on earth would I move across the country and complete a field season in a new research system while gestating, birthing, and then caring for a tiny human … all with no support system? I am privileged that both my Ph.D. and postdoc supervisors have been wonderful, but neither they nor I had any idea how to map out the transition from grad student to postdoc while I also navigated new motherhood. Despite a medically complicated pregnancy, I managed to meet or exceed the metrics set for me in my first year, thanks to the help of my colleagues and PI, and my son is now a vibrant 8-month-old.

Not all ECPs choose to have children, but working parenthood is more common than ever before, and many more women are working during pregnancy or while raising young children (Levi 2012). This is likely the result of a new focus on diversity, equity, and inclusion, including not discriminating against people that are pregnant or already have children. This new “approval” of female parents in progressing careers is a start, but currently, the intention seems to outweigh the effort. We must move past acceptance toward tangible institutional support with approaches that help parents and their supervisors navigate this exciting, important, and challenging time.

For example, as of 2018, only 17% of American workers had access to any paid parental leave (BLS 2019). It falls to workplaces to provide this, and some universities or state governments do, but paid time off to care for themselves and their new child should be guaranteed for ECPs whether they are postdocs, tenure-track faculty, or industry professionals (Morgan et al. 2018). Childcare availability in the U.S. is comparably abysmal and prohibitively expensive for many ECPs. If employers don’t provide on-campus childcare, they should offer subsidies so that parents can find and afford off-campus care for their children. Time off to have a child (and a safe place to put them while we work) are the absolute minimum needed for ECP parents to survive, but we could thrive with support like specialized mentorship, formal guidance on adjusting timelines (like tenure and grant funding) to account for maternity leave, and learning sessions for supervisor–employee communication, to name a few.

It stings an ECP parent to hear the oft- repeated phrase, “it takes a village to raise a child.” As folks just starting our careers, we are uprooted from the friends and family that would make up our villages. We are scientists—intelligent, creative, and driven—but we are set up to fail when we try to balance parenting and productivity with minimal support. If universities and industry workplaces want the fresh perspectives and resilient determination ECP parents offer, they must step up and help us build our village.

Katlyn Catron is a postdoc at Washington State University and works in cherry pest management. Her free time is occupied with keeping the aforementioned small human alive and the occasional nap.

References Cited

BLS (U.S. Bureau of Labor Statistics). 2019. Access to paid and unpaid family leave in 2018. TED: The Economic Daily, 27 Feb 2019.

Levi, M.D. 2012. How paid family leave affects mothers in the labor force. U.S. Bureau of Labor Statistics Monthly Review (Précis), March 2012: 66–67.

Morgan, A.C., S.F. Way, M. Galesic, D.B. Larremore, and A. Clauset. 2018. Paid parental leave at US and Canadian universities.

New Phenology Based Psylla Management

March 1, 2022

Pear Psylla Phenology IPM Guide will help manage pear psylla using the new degree day model!

As temperatures warm and the snow melts, it is time to think about pear psylla management. In warmer areas like Oregon and southern Washington, psylla are already back in the orchards and laying eggs. In central and northern WA, psylla will move into orchards once the snow melts.

IPM strategies for pear psylla provide optimal season-long control by utilizing selective sprays and cultural strategies to suppress psylla while conserving natural enemies. If you have ever wondered why psylla control falls off toward the end of the season, it is likely due to a lack of natural enemies from too many broad-spectrum sprays. This is why we encourage the use of selective management approaches, such as kaolin clay, insect growth regulators (IGRs), organic insecticides, and cultural techniques like tree washing and summer pruning.

In order to help you choose the right approach for your orchard and better understand the development of pear psylla in your region, WSU has created a pear psylla degree day model and associated management strategies. Visit the new page Phenology Based Pear Psylla Integrated Pest Management for the model and strategies. The website is a work in progress and subject to change as we continue to perform experiments and refine the conventional and organic management strategies.

Sustainable Control of Pear Psylla

mostly white slide with drawing of tree fruits in the lower left corner, a small video feed of the speaker in the upper right corner and the title be brave pear psylla management

February 22, 2021

Be BRAVE: Pear Psylla Management

On Thursday, February 18, 2021 as part of an OSU/WSU webinar, Stijn van Laer gave a talk on pear psylla management in northern European pear orchards.  Stijn is a crop consultant that works for company called FruitConsult based in Belgium.  They are a private consulting firm that does not sell products (i.e., chemicals), just management recommendations. Stijn discussed management of pear psylla in European orchards with conservation biological control (i.e., only using soft insecticides and at economic thresholds) and by augmentation of earwigs.  He also discussed the importance of proper sprayer calibration and how this can make or break effective management.

2021-2022 Pear IPM Study Circles

green anjou pear with droplets of water on the side

Join us for pear study circles this winter – they’re free!  It’s a great learning opportunity for growers, consultants, researchers, and industry professionals.  Our goal is to improve pear profitability and sustainability. Each study circle will include a 30 minute presentation and 2 hours of facilitated discussion.

Topics include:

  • Oct 19, 2021 – Choosing products that work: A discussion of pesticide efficacy
    2019-2021 research results from Louis Nottingham, WSU Entomology. Grower experience from the field.
  • Nov 23, 2021 – Honeydew Washing Systems – Adding a Cultural Control to your Toolbox
    2020 research results from Tianna DuPont, WSU Extension. Grower presented case studies.
  • Dec 14, 2021 – Using pear psylla phenology to better time applications
    Outline of the new psylla phenology model from Louis Nottingham, WSU Entomology. Examples of scouting information showing when the model has worked and when it has not. Brief intro to potential scouting app. Discussion of getting weather stations to improve accuracy. Discussion of how growers/consultants want to best access data.
  • Jan 11, 2022 – Assembling IPM programs that work
    Discussion of IPM and bio-based IPM programs step by step through the season and new research on natural enemy impacts of current products, Louis Nottingham, WSU Entomology.
  • Feb 8, 2022 – How can we integrate thresholds and scouting?
    Current research on thresholds for psylla and natural enemies. Input on phone application/website for data access.

Download a flyer here, or visit the WSU Tree Fruit web site events page for more information.  Hope to see you there!

Plant Defense Elicitors

November 18, 2021

Test of plant defense elicitors for arthropod pest suppression and PR-1 gene induction in pear orchards

Plant defense elicitors (PDEs) are chemicals that stimulate plant defenses against pathogens and herbivores. Previous work shows that PDEs acibenzolar-S-methyl (ASM) and harpinab protein (harpin) can induce the pathogenesis-related gene PR-1 in plants and suppress herbivorous arthropods. In this study, we tested the potential for these PDEs to induce PR-1 in pear, Pyrus communis L. (Rosaceae) orchards and suppress pear psylla, Cacopsylla pyricola (F€orster) (Hemiptera: Psyllidae), and spider mites, Tetranychus spp. (Acari: Tetranychidae). In 2017, we compared densities of each pest on mature pear trees following a single application of either an ASM product (Actigard; Syngenta), a harpin product (Employ; Plant Health Care), or no PDE treatment in four commercial and two research center orchards. In 2018, we sampled pear psylla and used qPCR to assess PR-1 induction in pear leaf samples before and after PDE treatments at one commercial orchard. Neither PDE treatment showed evidence of pest suppression in either year, and no differences in PR-1 expression were detected. Potted greenhouse trees treated with ASM in 2019 showed higher PR-1 expression relative to untreated trees, verifying that our procedures can detect induction and suggesting that a single PDE application was sufficient to induce PR-1 in potted but not mature pear trees. We conclude that plant defense elicitors may contribute to pear pest suppression in some contexts, but effects are unlikely to be strong or consistent. Our results highlight the need for field experiments to advance plant defense elicitor knowledge towards effective field applications.

Leafhopper Insecticide and Particle Film Summaries

4 leaves are in a shallow dish of dirt, in a white insect net cage

2020 and 2021 Leafhopper Insecticide Trials

By Dr. Louis Nottingham and Dr. Katlyn Catron


Colladonus reductus leafhoppers were collected from organic or unsprayed orchards’ groundcover (Fig. 1) via sweep nets, then returned to the lab. Leafhoppers were exposed to insecticides by direct sprays or previously treated leaves from cherry trees. After exposure, leafhoppers were kept in ventilated arenas with treated cherry leaves (Fig. 2) for 24-48 hours, then rated as alive or dead. Between 25-50 leafhoppers were examined per treatment in each experiment.

Combined 2020 & 2021 Results:

Columns show average percentage mortality (dead ÷ total x 100) from each insecticide and exposure type. Values above dotted line are averages from at least two trials; below are from a single trial.

2021 Particle Film and Oil Repellency Trial

By Dr. Louis Nottingham and Dr. Katlyn Catron


Leafhoppers were collected from orchard groundcover and returned to the lab. Forty leafhoppers were added to cages with leaves treated with either H20, IAP oil 1%, Surround WP (kaolin) 50 lb/acre, or Celite (diatomaceous earth) 50 lb/acre (Fig. 3). Four experiments were conducted. In the first two, Surround and Celite were mixed with 1% oil, in the second two, no oil was mixed with these two products. Two visual evaluations were conducted for each experiment, (5 hours and 24 hours after treatment) to determine how many leafhoppers occupied each leaf.


Leaves treated with Surround or Celite had the fewest leafhoppers, followed by 1% Oil (Fig. 4). Some leafhoppers were found on Surround, and Celite treated leaves, generally in areas with less or no particle film residues. Although particle films demonstrated significant repellency in this test, more testing is needed to understand if particle films or oil can reduce the spread of x-disease phytoplasma.

Fig. 4. Presence of leafhoppers on treated leaves. Treatments not sharing a letter are significantly different.

Funding: Thanks to the WA Tree Fruit Research Commission and OR Cherry Groups for research funding.

**Use pesticides with care. Apply them only to plants, animals, or sites listed on the labels. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions; it is a legal document. Always read the label before using any pesticide. You, the grower, are responsible for safe pesticide use. Trade (brand) names are provided for your reference only. No discrimination is intended, and other pesticides with the same active ingredient may be suitable. No endorsement is implied.