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2022 WA Tree Fruit Research Commission Grant Awards for Apple Horticulture and Postharvest

Written by Paige Beuhler and Ines Hanrahan, March 2022

For 2022, the WA Tree Fruit Research Commission approved $303,080 to help fund four (4) new Apple Horticulture and Postharvest projects.

2022 New Apple Horticulture and Postharvest Project Details:
Project Title: Reducing CO2-related disorders during Honeycrisp rapid CA treatment
Organization (s): USDA-ARS
PI (s): Rudell, D.; Mattheis, J.
Total Funding Amount for All Years: $190,000
Length: 3 years
CO2 sensitivity continues to be a risk for postharvest losses of important cultivars including Honeycrisp. Both internal and external disorders resulting from elevated CO2 during storage are often confused with disorders merely caused by chilling alone, including soft scald and soggy breakdown. Temperature conditioning at 50°F is a widely accepted industry practice to reduce chilling injury (soft scald or soggy breakdown). While there has been some industry adoption of rapid CA during temperature conditioning, its acceptance would be greater if technical issues due to increased disorders linked with this protocol, including those related to elevated CO2 during this procedure, were addressed. The project’s specific goals (Anticipated benefits) are to provide information to aid in avoiding external and internal browning caused by CO2 sensitivity during rapid CA conditioning of Honeycrisp. The goals and objectives address industry priorities “understanding/managing/reducing decay and physiological disorders”. Realizing these goals will provide storage management guidelines to reduce development of multiple postharvest physiological disorders of Honeycrisp while enhancing fruit quality throughout the cold chain.


  1. Determine influence of CO2 levels on disorder development during rapid CA treatment.
  2. Determine impact of initial fruit temperature and delay of CA establishment during conditioning on disorder development.
  3. Monitor flesh chemistry to indicate which treatment conditions may elevate risk of developing soft scald/soggy breakdown or CO2-related/other disorders.

Project Title: Measuring the impact of leaf removal on spur and tree health
Organization (s): Washington State University
PI (s): Kalcsits, L.; Lewis, K.
Total Funding Amount for All Years: $179,301
Length: 3 years
There has been a significant adoption and/or interest in leaf removal practices (manually or mechanically) to improve red color. However, the impact of the severity of leaf removal on spur and tree health is unknown and needs to be more carefully evaluated. This project addresses the priority identified in the Request for Proposals to “Develop best practices to manage and increase over color.”


  1. Quantify improvements in leaf color and changes to sunburn incidence from leaf removal for an early and late-season bicolor apple cultivar.
  2. Determine whether differences in leaf removal severity and timing before harvest impacts energy and nutrient storage and subsequent spur health the following season or an early and late-season bicolor apple cultivar.
  3. Develop practical operating guidelines and economic cost-benefit thresholds for leaf removal based on commercial trials in WA.

Project Title: Towards next generation maturity indices: apple biomarker discovery
Organization (s): USDA ARS, Washington State University
PI (s): Honaas, L.; Ficklin, S.; Harkess, A.; Mattheis, J.
Total Funding Amount for All Years: $319,976
Length: 3 years
An emerging frontier to optimize postharvest management of apple fruit is the use of
genomics studies, integrated with machine learning (ML) methods to discover biomarkers. Unlike
markers that breeders use, postharvest biomarkers could be used to optimize fruit storage for
predictable outcomes (e.g., texture, disorders). Such biomarkers could add to the postharvest toolbox
for managers, but also to the research toolbox for future studies in postharvest tree fruit quality. Honaas’ pome biomarker team is taking a multifaceted approach to biomarker discovery; they are building essential genome resources, exploring and developing new methods for discovery of gene activity biomarkers, and building an ever-growing sample catalog to validate biomarker candidates. The team is working towards a deeper understanding of pome fruit maturity that may lead to the development of a high-performance NGMI (Next Generation Maturity Indices). Initially, an NGMI would likely be useful for relative comparisons, especially where current maturity indices show no difference.


Develop and improve methods for biomarker discovery.

  1. Use novel analytics and modeling approaches to strengthen biomarker discovery approach
  2. Generate new global-scale gene activity data from current and new multi-year samples for rapid validation
  3. Investigate disagreement between technologies for gene activity estimates to enhance translation to NGMIs

Project Title: Mitigating WA 38 greasiness and related quality defects
Organization (s): Washington State University, USDA-ARS TFL
PI (s): Torres, C.; Rudell, D.
Total Funding Amount for All Years: $254,154
Length: 3 years
Peel greasiness can develop any time prior to and throughout the cold chain on many economically important cultivars, especially WA 38 (reducing greasiness is a FY 2022 priority). Besides diminished appearance, greasiness or, potentially, mitigation using high amounts of fruit finish aids (waxes and/or shellac) can be associated with off-flavors. Greasiness is influenced by weather during fruit development and growth, harvest maturity, and storage temperature and atmosphere, and can be reduced by proper harvest, CA storage protocols, and post-storage wax/coating applications.
The team proposes to develop new strategies to reduce or eliminate greasiness in the WA 38 post-storage cold chain. The researchers will account for differences in harvest maturity with special focus on later picks that include fruit of high storage quality but are already greasy when placed in storage. They will use combinations of ethylene mitigation (pre- harvest, postharvest, and/or post-storage 1-MCP as well as AVG preharvest), controlled atmosphere, de-greasing, and post-storage cold chain (distribution, transport, and retail) to develop these strategies. For mitigating off-flavors, they will determine conditions associated with off-flavors, determine natural chemicals or interactions associated with the off-flavors, and, finally, define strategies that reduce or eliminate off-flavors. Expected outcomes include strategies devised to reduce or eliminate WA38 greasiness and associated off-flavors.


  1. Further define harvest maturity guidelines limiting greasiness of WA 38 in the cold chain.
  2. Establish ethylene mitigation protocols that reduce WA 38 greasiness for both conventional and organic production.
  3. Determine the limitations of wax/detergent for mitigating wax in the post-storage cold chain.
  4. Identify and determine protocols for mitigating off-flavors associated with greasiness


Paige Beuhler (Administrative Officer):, 509 665 8271 ext. 2
Ines Hanrahan (Executive Director):; 509 669 0267


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