Skip to main content Skip to navigation

New Pear Research Projects 2021-2022

View Print Version

Written by Torry Schmidt, August 2021

Based on the recommendations of the Pear Research Subcommittee, the Fresh and Processed Pear Committees jointly approved funding for 7 new pear research projects for 2021-2022 totaling roughly $300,000 for the current season. Progress on these projects will be reported at the Northwest Pear Research Review in February 2022; details on how to participate in this meeting will be posted later this fall.

As always, final reports for completed research projects funded by the Fresh and Processed Pear Committees, as well as apple, cherry, and technology projects funded by the Washington Tree Fruit Research Commission, are available.

Project Title: Biological control of Brown Marmorated Stinkbug using Trissoicus japonicus

Organization (s): Oregon State University
PI (s): Chris Adams
2021-2022 FPC/PPC funding: $30,550
Project duration: 3 years
The Invasive brown marmorated stink bug (BMSB) (Halyomorpha halys) has been reported in all but four states in the U.S. including Washington and Oregon. It is now established in the Mid-Columbia growing region and is emerging as a major threat to tree fruit production, causing economic damage in pear orchards there. The frequent pesticide control measures, needed to protect valuable tree fruit in Mid-Atlantic States, has disrupted established IPM programs and is unsustainable. One of the most promising control tactics is a biological control agent Trissolcus japonicus (Tj), a parasitic wasp that attacks the eggs of BMSB. Despite the promise of Tj providing effective biocontrol of BMSB, there is much to learn about the potential for establishment in PNW pear orchards and how best to introduce this biological control.
Objectives:
1. Raise and release Tj season long in key locations (every year)
2. Measure establishment using sentinel egg masses and yellow sticky traps (years 2 & 3)
3. Describe the habitats where wasp establishment is most successful (years 2 & 3)
4. Measure the effectiveness of Tj biocontrol for preventing fruit damage (years 2 & 3)

Project Title: Calibrating current natural enemy thresholds with lure-baited trap catch

Organization (s): Oregon State University
PI (s): Chris Adams
2021-2022 FPC/PPC funding: $30,095
Project duration: 3 years
Biological control services provided by natural enemies (NEs) are a key part of pear integrated pest management in the Mid-Columbia region. Crop consultants scout for both psylla and natural enemies to estimate the building pest population and the level of control that can be expected. Monitoring currently requires considerable time and effort to gather enough data to be confident in these decisions. Additionally, these NE thresholds are experience based and each consultant may have their own threshold for deciding if sprays are needed or not needed. Quantifying and standardizing these action (or inaction) thresholds by developing lure baited monitoring systems would improve area-wide IPM decisions and help new younger (less experienced) consultants have greater confidence in their recommendations.
Working in collaboration with local crop consultants, we will place plant-volatile baited and other NE traps, in orchards throughout the Hood River and Washington pear-growing regions and compare catch data with current scouting practices. We will monitor relative abundance and diversity of NE capture over a period of three years. While different orchards will have different species complexes, we hope to demonstrate that monitoring traps can give consultants accurate relative abundance estimates of key indicator species that they scout for, saving time and increasing confidence in management recommendations.
Objectives:
1. Use plant volatile baited monitoring traps to describe NE communities in orchard ecosystems.
2. Compare capture of several key species of NEs in lure-baited traps with numbers measured from standard scouting techniques.
3. Establish action (or in-action) thresholds for key NEs.

Project Title: Tactics to improve natural enemy releases in tree fruit

Organization (s): United States Dept. of Agriculture – Agricultural Research Service
PI (s): Rebecca Schmidt-Jeffris
2021-2022 FPC/PPC funding: $51,279 (Note: this project has also received $350,000+ in funding from other sources)
Project duration: 2 years
Pear growers are experimenting with releasing natural enemies, primarily targeting pear psylla with releases of Orius insidiosus (minute pirate bug) and Chrysoperla rufilabris (green lacewing). Organic management options for pear psylla are limited and conventional programs would benefit from being able to successfully release natural enemies for pest control. The pervasive uncertainty associated with natural enemy releases clearly points to a need for more thorough research on commercial release strategies.
Pear growers in particular could benefit from releases; in the years after transitioning from conventional to IPM or organic, purchasing and releasing natural enemies could “fill the gap” while growers wait for resident natural enemy populations to build. Natural enemy releases could also assist with late season outbreaks, allowing growers to avoid pesticide applications that could potentially disrupt the natural enemy community that they have worked hard to build. The two natural enemy species we will test in this project, O. insidiosus and C. carnea, are found “naturally” in Washington orchards; therefore, releases of these species may allow growers to establish predator populations that assist with biological control in future years. This proposal is for a two-year project that will examine strategies to improve natural enemy retention, survival, and pest management efficacy in pears, with complementary funding requested from Apple Crop Protection.
Objectives:
1. Improve retention of released natural enemies.
2. Determine cost-effectiveness and efficacy of natural enemy release by drone.

Project Title: Development of a rapid-cycle breeding tool for pear

Organization (s): United States Dept. of Agriculture – Agricultural Research Service
PI (s): Jessica Waite
2021-2022 FPC/PPC funding: $32,915
Project duration: 3 years
For PNW pears specifically, Pyrus-compatible, fire blight resistant, cold-hardy, precocious, dwarfing rootstocks would be ideal, however existing varieties to choose from are quite limited in these traits. A major limitation for rootstock breeding is the long juvenility period (reaching ~10 years in European pear trees), particularly for combining, or stacking, multiple traits, as this requires numerous rounds of crossing. While DNA-informed breeding can speed the selection process, breeding cycles are still 5-10 years, meaning variety releases are 20-40 years from initial crosses, depending upon the breeding scheme. To speed up this process, researchers working in other temperate trees including plum, apple, and citrus have used biotechnology to develop rapid-cycle breeding (RCB) tools to stack traits in a greatly reduced amount of time. Existing RCB tools work by modifying flowering gene expression, leading to premature or even continuous flowering, dramatically reducing the lengths of breeding cycles, and enabling year-round breeding within the greenhouse.
While RCB systems are functional in apple, plum, and citrus, continuous flowering throughout breeding cycles can create challenges. These include balancing vegetative and reproductive growth, as well as the accumulation of terminal floral meristems that lead to growth cessation. Early flowering has been demonstrated in pear by groups in Israel and Japan, however an RCB system has not been developed in the US, nor in rootstock germplasm that would be of most interest to the PNW region. To develop a system for rapid breeding of pear rootstocks and avoid the drawbacks in existing systems, we propose to introduce an inducible RCB system, the tools for which were recently developed in the Cutler lab and successfully applied to citrus.
Objectives:
1. Transform pear rootstock germplasm with a flowering-activating, chemically-induced system.
2. Early molecular and phenotypic characterization of transformants.
3. In-depth characterization and optimization of RCB plants.

Project Title: Field evaluation and propagation of cold-hardy quince rootstocks

Organization (s): Michigan State University, Washington State University, Oregon State University
PI (s): Todd Einhorn, Stefano Musacchi
2021-2022 FPC/PPC funding: $32,915
Project duration: 3 years
In Europe, quince is the preferred rootstock for intensive pear production, facilitating high-density, productive and efficient orchards that are amenable to mechanization and labor-saving technologies. Quince rootstocks are highly dwarfing, precocious, and confer high productivity and large fruit size to pear scions, unlike rootstocks from the genus pear (Pyrus sp.). However, insufficient cold hardiness is the critical weak link for the adoption of quince in northern growing regions like the PNW. With previous funding from the NW Pear Committee, we conducted a three-year cold-hardy evaluation of over half of the core collection of quince germplasm maintained at the USDA-NCGR, in Corvallis, Oregon. These clones maintained their cold hardiness to levels similar to OH × F 87 and 97. Only a few of these quince clones were developed as dwarfing pear rootstocks in other countries; most of these quince accessions, however, have never been evaluated as size-controlling pear rootstocks.
In a subsequent multi-year project funded by the NW Pear Committee, we developed additional information on this cold-hardy quince population relative to their ease of propagation and fire blight tolerance (work performed by USDA colleagues at Corvallis, OR and Kearneysville, WV). At the completion of the project, North American Plants, Inc. had successfully tissue cultured roughly half of the cold-hardy selections (9 of the 20 accessions) using a standard media. These were rooted and sent to a nursery to facilitate the establishment of two field performance trials (one in WA and one in OR); the subject of our recent three-year funded project (ending in 2020). These performance trials have yielded exciting results, and several selections have proven to be precocious, size-controlling, and productive for ‘Bartlett’ and/or ‘d’Anjou’ (see 2020 Final Report and webinar). How these rootstocks will perform in the next cropping years will be critical to determining their potential commercial value. We are proposing to continue the important research of observing, training, and measuring tree growth, productivity, and fruit quality performance for the upcoming cropping years (e.g., years 4-6). In this proposed public-commercial partnership, we intend to develop micropropagation protocols to successfully establish those accessions. The deliverable for this component of the project is a subset of trees to facilitate a subsequent field performance trial with previously unexplored cold-hardy quince accessions. Importantly, we additionally propose to bulk up the supply of high-performing quince rootstocks from our current field trial to facilitate a pipeline for commercialization should these continue to perform well in years 4-6. Thus, at the conclusion of this proposed project, we intend to have a supply of the high-performing quince rootstocks ready for larger-scale field trials with interested growers (in selection/breeding programs, this is commonly referred to as Phase 3 evaluations).
Objectives:
1. Continue to evaluate vegetative and fruiting performance of Bartlett and d’Anjou pear trees on nine quince rootstocks in current field performance trials (WA and OR), and successfully micropropagate the remaining 11 cold-hardy quince selections for establishment in new field performance trials.

Project Title: Survey of pear packers on storage and handling of Anjous

Organization (s): Washington State University
PI (s): Carolina Torres
2021-2022 FPC/PPC funding: $15,975
Project duration: 1 year
Eating quality on pears is key to maintain and increase its consumption. In winter pears, like Anjou, this is a challenge, especially after short-term storage, because of their chilling requirement to ripen and their variable maturity stage at harvest. Today, the WA pear industry has different handling practices for this variety with variable success, especially in early season fruit. There is a need in the industry to develop universal metrics and standards to define “good” vs. “bad” fruit, additionally to identify and define the best storage practices being used. This is an opportunity to better understand how the industry can extend the storage and marketing season and still deliver high eating quality fruit. A survey will help to identify best practices to help the industry. Previously, a survey was carried out by Gene Kupferman in the 90s (Tree Postharvest Journal, 1998); since then, new technologies such as 1-MCP have changed some of those practices, as well as the fruit outcome. Therefore, a new survey will update some of this information together with anonymous fruit quality.
Objectives:
1. Obtain information about varied storage and handling practices of Anjou pears from multiple warehouses.
2. Correlate different storage and handling practices with fruit quality.

Project Title: Pear consumer preference testing

Organization (s): Washington State University, Oregon State University
PI (s): Carolyn Ross, Ann Colonna
2021-2022 FPC/PPC funding: $49,980
Project duration: 1 year
In recent years, consumers’ expectations of their fresh pears have increased, creating a need for higher quality pears. One of the major factors that has been shown to influence fruit quality are the sensory characteristics. The visual sensory characteristics such as size, color, and scarring play an important role in initial purchasing. However, consumers’ repurchasing habits are influenced more by the flavors, aromas, tastes, and textures. Therefore, understanding the sensory characteristics of different pear varietals and their influence on overall quality is critical. Information regarding pears preferences and preferred sensory properties of pears can then be used to select existing varieties for more aggressive marketing, as well as provide priority traits for breeding targets in a pear breeding program.
The objective of this research proposal is to identify the pear sensory characteristics considered to be desirable by consumers in the Pacific Northwest (PNW). Previous research has provided information regarding the traits that make a well-liked pear, but this current research project proposes testing new varieties and seeking to understand what sparks consumer interest in pears in the current PNW consumers.
Objectives:
1. Perform a literature review on all known existing pear consumer acceptability studies
2. Identify pears varieties with varied sensory properties in consultation with qualified and experienced individuals and groups
3. Conduct trained sensory panel profiling of pears
4. Complete consumer testing of pears, including acceptability and willingness to pay
5. Perform data analysis to understand the relationships among sensory properties (from the trained panelists) to consumer liking and willingness to pay.

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.

Washington State University