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WSU Tree Fruit

2021 WA Tree Fruit Research Commission Grant Awards for Apple Horticulture, Postharvest, and Crop Protection

Written by Ines Hanrahan, Amy May, and Mackenzie Perrault, May 2021


In 2021, the WA Tree Fruit Research Commission approved $1,396,455 to help fund twenty-seven (27) new projects in the areas of cherry, apple, and technology. In apple research, the Commission approved $745,796 to fund fifteen (15) new projects in the areas of apple horticulture, postharvest and crop



2021 new apple project details:


Apple Horticulture and Postharvest (10 new projects)


Project Title: Apple crop load management

Organization (s): Washington Tree Fruit Research Commission

PI (s): Schmidt, T.

Total Funding Amount: all costs are covered through outside funding

Length: 3 years

Growers need multiple management tools to produce consistent yields of high-quality fruit; some of the most important tools for effective crop load management currently are chemical thinners and plant growth regulators. While there are multiple chemicals currently registered for these purposes, some of them (i.e., carbaryl) are under regulatory and consumer/market pressure, and nearly all of them can be imprecise and sometimes unreliable in their efficacy. With the goal of developing strategies to minimize physical and financial inputs while producing crops that bring profitable returns to growers, this project proposes exploring novel approaches to chemical thinning and the use of plant growth regulators as well as collaboration on a national Specialty Crop Research Initiative (SCRI). The collaboration will target precision crop load management with a focus on developing predictive crop load models, automation of crop load management operations, and advancing the current understanding of the physiological principles that underpin cropping in apple trees.



Project Title: Retraction of netting near harvest: risks vs. rewards

Organization (s): Washington State University

PI (s): Kalcsits, L.

Total Funding Amount: $76,868

Length: 2 years

This project addresses key industry questions on the timing of netting retraction and the use of supplemental evaporative cooling to mitigate sunburn risks during retraction.

The development of retractable netting systems provides options for rapid retraction and deployment of netting near harvest to respond to changes in environmental conditions where sunburn risks are lower. These management decisions can rapidly increase light reaching the fruit surface promoting red color development. There may also be elevated risks associated with these decisions including the stimulation of sunburn browning and photooxidative sunburn in recently uncovered fruit. However, there is currently no knowledge of how fruit responds to small increases in light exposure and whether that is enough to induce sunburn browning or photooxidative sunburn on fruit. The use of retractable netting systems creates opportunities to optimize the light environment to promote red color development near harvest but also protect from sunburn in July and August during hotter times of the year.


Project Title: Efficient heat stress management for improved apple fruit quality

Organization (s): Washington State University

PI (s): Khot, L.; Sallato, B.; Torres, C.; Peters, T.

Total Funding Amount: $202,984

Length: 3 years

This project aims to investigate efficient heat stress monitoring and management strategies in Honeycrisp and WA-38 apple cultivars with the goal of reducing in-field and post-harvest crop losses.

It addresses multiple research priorities identified by the WTFRC including 1) Abiotic stress management by better understanding of physiological, environmental factors affecting maturing fruits; 2) Understanding heat damage of fruits and associated maturation patterns as well as storage potential based on in-season climate data; and 3) Achieving overall sustainable production and consistent fruit quality for profitable orchards through non-contact sensing and energy/water efficient heat stress management — optimized for two premium apple cultivars. Three critical outcomes are anticipated with this project:  1) a better understanding of effective, appropriate heat stress management techniques, potentially including an efficient energy/water use solution in apple crop stress (sunburn) management; 2) insight into within-season heat stress and the associated fruit losses at harvest and afterward in storage; and 3) the suitability of real-time noncontact sensing for block specific management.


Project Title: Maximize pollination window to improve fruit set in WA 38

Organization (s): Washington State University

PI (s): Serra, S.; Musacchi, S.; Schmidt, T.

Total Funding Amount: $145,835

Length: 2 years

The abundant bloom of WA 38 does not necessarily translate to a high fruit set; the variety demonstrates a natural shedding trait with the capacity to retain at least one fruit/cluster in just 66-67% of the flower clusters. Hence, this research study will help develop strategies for improving fruit set in WA 38. Pollination and successful fertilization are major factors influencing fruit set and development, and ethylene signaling is responsible for the post-bloom fruitlet drop. AVG and 1-MCP, know ethylene action/synthesis inhibitors will be used to explore the significance of ethylene signaling in WA 38 fruit set. Second, we will modify the light environment around trees by deploying reflective fabric. The increase in diffuse light in the most shaded portions of the canopy should improve flower bud formation and contribute to keeping regular production.


Project Title: Managing calcium related disorders in high vigor conditions

Organization (s): Washington State University

PI (s): Sallato, B.

Total Funding Amount: $42,135

Length: 3 years

The main factors that predispose WA apple orchards to Ca related disorders can be grouped into three general conditions: 1) deficient Ca supply, 2) excessive vigor, and 3) stress conditions during fruit ripening. A current SCBG project will continue focusing on the first group: managing soil Ca availability and supply during spring (in sites where those factors have been identified as most limiting). This project will address the second factor: excessive vigor. In South Central WA, excessive vigor was associated with elevated levels of N (especially during orchard formation), high water and nutrient retention in soils, and rootstock. In a total of 129 sites, more than 90% were silt loam with a low to moderate infiltration rate. More than 40% of Honeycrisp are grown on medium to large vigor rootstocks (M7, M106, M26, Bud 118). Taking into consideration all possible factors that could lead to Ca related disorders, this project will carefully select four blocks where excessive vigor has been identified as the most limiting factor.

Complementary proposals have been submitted addressing stress management. Therefore, all three predisposing factors leading to Ca deficiency disorders incidence in the fruit will be approached to effectively control these disorders under WA commercial conditions.


Project Title: WA 38 applied research and demonstration block

Organization (s): Washington State University

PI (s): Sallato, B.; Khot, L.; Bolivar-Medina, J.

Total Funding Amount: $25,245

Length: 3 years

Since 2018, the Roza block has been managed by Sallato’s program, supported by industry collaborators and donations (e.g., Bleyhl’s support on pest and disease management, GS Long with fertilizer products, Burrows tractors for platforms, among others). South Central WA growers have served as advisors of management practices that align with commercial growing conditions and help to identify emerging issues. As a result, the Roza WA 38 block has become a platform to develop an engaged community to learn about a diverse array of topics. To enable representative and valuable information for growers, research regarding horticultural practices requires at least 4 years to account for environmental changes, biennial bearing, tree balance, etc. However, most funding resources suited for applying research projects have a 3-year maximum time frame (WTFRC, WSDA-SCBG, others). This project is requesting support to continue the evaluation of horticultural practices for vigor management, production, and green spot on 8-year-old WA 38 block at the WSU Roza farm.


Project Title: Bilingual extension program for WA 38

Organization (s): Washington State University

PI (s): Bolivar-Medina, J.; Sallato, B.

Total Funding Amount: $22,000

Length: 2 years

Although most of the workforce in the industry are Spanish native speakers, the extension programs have been developed mainly in English. This situation can interfere with a clear and effective transmission of the information and smooth technology adaption within most of the industry communities. The goal of this project is to broaden the scope and outreach capacity of WA 38 / Cosmic Crisp® extension programs and to be more inclusive by providing educational products in Spanish for the largely Hispanic industry community.


Project Title: WA 38: SOP from planting to cropping

Organization (s): Washington State University

PI (s): Musacchi, S.; Serra, S.; Lewis, K.; Sallato, B.

Total Funding Amount: $266,675

Length: 3 years

In this study, we aim to investigate a protocol to develop an orchard from planting to year 3. With the knowledge that the rootstock has significant effects on the variety in terms of vigor, growth, flower bud formation, and productivity, the plan is to plant a new WA 38 block where the cultivar is grafted on seven different rootstocks widely adopted in the WA industry: G935, G969, G41, G11, Bud9, M9337, and M9-NIC29. Farming this block from planting to cropping for research purposes will allow for comparison between the flower bud formation, fruit set, yields, and bud extinctions in the different rootstock/cultivar combinations. Further, the project will investigate the management practices adopted in private orchards. These two tasks combined will have the final goal of creating a standard operating procedure (SOP) for the growers to achieve consistent yield with step-by-step instructions customized for each rootstock and in the context of degree of vigor. This research will be complementary and will leverage the research subjects listed in the recently funded NIFA SCRI project on Precision Crop Load Management for Apple.


Project Title: Reliable soil diagnostic technology for smart nutrient management

Organization (s): Washington State University

PI (s): Sallato, B.; Khot, L.

Total Funding Amount: $30,640

Length: 2 years

The challenge with soil nutrient technology is the inexistence of the ground-truthing method, which leads to a more basic question: How to better estimate nutrient availability for tree fruit crops?

The goal of this project is to develop “smart nutrient management,” where growers could prescribe not solely chemical applications but also soil amendments (e.g., acidifiers, microbiological, root growth promoters, etc.) more efficiently and precisely, based on quantifiable needs. For such efforts, we need the team will to: 1) investigate tools that can assess and map soil variability accurately, and 2) explore testing methods that reflect response (e.g., growth, vigor, fruit quality). The value and reliability of a soil test is defined by its ability to indicate nutrient availability, deficiencies, or toxicities, and one that correlates best with plant response. A reliable method should then be i) accurate; give a correct value, ii) sensitive; detect changes in nutrient availability/management, and iii) stable; while sensitive, it should also be stable and representative of the period it covers. Finally, efficient methods/technology should also consider the practicality of the process, which includes cost, sampling frequency, level of difficulty of the sampling process, data handling, and ultimately, adequate interpretation.

Note: This project is part of the Smart Orchard project initiated by WTFRC in 2020.


Project Title: Evaluation of an alternative postharvest fungicide applicator

Organization (s): Washington State University

PI (s): Critzer, F.; Amiri, A., Hoheisel, G.

Total Funding Amount: $248,286

Length: 3 years

Traditional fungicide drenching poses a potential risk for cross-contamination with chemical, biological, and physical hazards. Jason and Jordan Matson with Matson Fruit felt that an alternative fungicide spray applicator for in-field application of binned fruit without water reuse may prove to be a viable alternative and would eliminate the risk of decay pathogens that can occur during traditional drenching. The hypothesis is that single pass fungicide spray systems are capable of adequately delivering fungicide with similar coverage to currently used truck drenching systems with decreased food safety risks due to lack of cross-contamination. Our The multi-disciplinary research team will seek to determine 1) optimized conditions for alternative sprayer settings with apples, 2) the efficacy as compared to traditional drenching systems for control of postharvest decay, 3) evaluation of water and apple microbiological quality compared to traditional drenching to seek alignment with food safety regulatory expectations, 4) alignment of expectations for an alternative fungicide sprayer with that of other regulatory bodies such as Washington Department of Ecology, and 5) communication of findings with apple and allied industries.


Apple Crop Protection (5 new projects)


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

Organization (s): USDA-ARS, Wapato

PI (s): Schmidt-Jeffris, R.; Nottingham, L.

Total Funding Amount: $208,591

Length: 2 years

Growers making large investments in natural enemy releases deserve greater certainty of success, which could be achieved with research-based guidance. This proposal, which requested and received complementary funding from FPC/PPC Pear, is a two-year project that will examine strategies to improve natural enemy retention, survival, and pest management efficacy in apples. Methods will be tested in large plots of commercial apple and pear orchards with growers who are currently attempting predator releases. Findings will be used to leverage additional funding from federal grants (targeting USDA NIFA OREI in January 2024) to expand these trials to further improve methods for predator releases.


Project Title: Phase 2: New biocontrol strains from WA native plants

Organization (s): University of Washington, Washington State University

PI (s): Doty, S.; DuPont, T.

Total Funding Amount: $34,219

Length: 1 year

A largely untapped resource for new biocontrol strains is the natural plant microbiome of Washington native plants. With Phase 1 funding from WTFRC, in vitro screens of microbial strain collections were tested against the pathogens that affect apple trees and fruits. Sixteen previously isolated strains showed inhibitory activity. Also included in Phase 1 of the project was the isolation of over a hundred new strains, which were sourced from native plants in natural areas near to apple growing regions (Yakima, Entiat, Wenatchee, and Methow). A few dozen of the new strains also inhibited the growth of some of the apple pathogens. In this Phase 2 proposal, the top performing new isolates will be subjected to full genomic sequencing and identification. The best performing microbial strains will be taken to the next stage toward commercialization of multiple biocontrol strains against key pathogens of high concern to the apple industry. These include common storage decays, patulin and fireblight.


Project Title: Detection of sources of patulin contamination in processed apples

Organization (s): Washington State University, University of Idaho

PI (s): Amiri, A.; Lee, H.J.

Total Funding Amount: $266,322

Length: 3 years

This three-year project aims to better understand the sources and the causal agents of patulin contaminations in processed fruit as well as to improve patulin detection. In 2018 and 2019, fruit processors in Washington have reported unusual, elevated levels of patulin (>200 pb) at the core and in the flesh of freshly harvested organic and conventional Gala and Honeycrisp apples with no apparent decay symptoms. These observations do not correlate with Penicillium epidemiology and with patulin being a problem of older and potentially contaminated fruit (>6 month in storage). Assessing patulin contaminations of fruit through the supply chain in a timely manner is challenging mainly due to the complexity of the processing chain and the absence of easy and accurate patulin detection assays. Although processors set requirements on fruit lots they receive for processing, there is a need to enhance collaboration and communication between them, growers, and packers to reduce fruit contaminations and alleviate patulin contaminations downstream. A stream-lined decision-making process is warranted to enhance product quality and safety.


Project Title: Genetic engineering of moth viruses for enhanced insecticidal efficacy

Organization (s): USDA-ARS, Wapato

PI (s): Walker, W.; Neven, L.

Total Funding Amount: $180,000

Length: 3 years

This proposal targets the highest WTFRC research priority, codling moth. Research will address the highest priority for codling moth, “product efficacy testing of current and new materials.”

Increased attention has been given to control strategies other than chemicals due to toxic effects on the environment and non-targeted organisms, as well as increasing prevalence of insecticide resistance. Codling moth granulosis virus (CpGV) has been studied over the past 50 years as a viable alternative to chemical control. This study will develop and assess novel strains and formulations of CpGV and a novel nuclear polyhedrosis virus (NPVs) called CrpeNPV. In addition to the development of potential products, fundamental knowledge may be gained about CpGV genes that contribute directly to viral infectivity and efficacy; this may indirectly lead to improved utility of CpGV in codling moth control beyond the scope of the objectives of this proposal.


Project Title: Directing plant-microbe relations towards resiliency post fumigation

Organization (s): USDA-ARS, Wenatchee

PI (s): Somera, T.; Mattheis, J.

Total Funding Amount: $99,961

Length: 2 years

Currently, there are no standard management practices used to counteract the adverse effects of fumigation on the soil microbiome. Replant sites, where resident soil microbial communities have been impaired by fumigation, are particularly well-suited for testing the impact of soil amendments on orchard soil restoration. Following fumigation, the application of soil amendments may be crucial and be the opportune time to improve the ability of the soil to defend against pathogen reinvasion as well as improve orchard productivity for an extended period. To date, the possibility of using soil amendments, including mustard seed meal, to suppress pathogen re-infestation of fumigated soils has not been tested.




Amy May (Administrative Officer):, 509 665 8271 ext. 2

Ines Hanrahan (Executive Director):; 509 669 0267