Written by Paige Beuhler and Ines Hanrahan – December 2024
For 2025, the Washington Tree Fruit Research Commission (WTFRC) approved $424,284 to help fund five (5) new projects. The Oregon Sweet Cherry Commission (OSCC) is co-funding three (3) projects, and the Northwest Nursery Improvement Institute (NNII) contributed $30,000 to two (2) new projects.
2025 New Cherry Project Details:
Project Title: A Field-Deployable Diagnosis of XDP Based on Optimized Cas12a Method
Organization (s): Washington State University, Penn State University
Principal Investigators (s): Zhao, Y., Yang, Y., Harper, S., Kesharwani, A.
Total Funding Amount for All Years: $183,029
Length: 2 Years
In a previous Washington Tree Fruit Research Commission funded project titled “Cas12a-Based Rapid Method for Early Detection of X-Disease Phytoplasma,” Zhao’s team developed a sensitive and specific RPA/Cas12a assay for rapid detection of the X-disease phytoplasma (XDP) which can be completed within 30 to 60 minutes in a high throughput manner with a 384-well fluorescence microplate reader. In addition, they developed a rapid genomic DNA extraction method for RPA/Cas12a assay, which can be completed within 5 minutes. However, the current approach is based on quantification of the relative fluorescence value using a microplate reader in a lab setting, which prevents the assay from being field deployable, and the costs of the required equipment are high. Zhao’s team plan to develop a field-deployable diagnosis of XDP, based on the optimized RPA/Cas12a method previously developed.
Objectives:
- To optimize one-pot RPA/Cas12a assay for field-deployable diagnosis using Genie III devise or visual detection method.
- To validate, apply, and recommend the field-deployable RPA/Cas12a assay for field sample diagnosis.
Project Title: Identifying Sources of Resistance to Pseudomonas and Powdery Mildew
Organization (s): Washington State University
Principal Investigators (s): McCord, P., Peace, C., Johnson, A.
Total Funding Amount for All Years: $26,655
Length: 2 Years
Bacterial canker (caused by Pseudomonas bacteria) and powdery mildew (caused by the fungus Clandestina cerasi) are two economically important diseases of sweet cherry in the Pacific Northwest. Incidence of canker is increasing, and durable genetic sources of resistance to powdery mildew are needed to avoid the spread of fungicide-resistant strains of the disease. For bacterial canker, resistant individuals have been identified, but genetic characterization remains to be done, i.e. the location and influence of resistance factors still need to be identified. Furthermore, many of the varieties in the USDA-ARS collection are not of commercial fruit quality; using them as parents for resistance would likely result in offspring with fruit too small or too soft for commercial use. Therefore, a similar screen needs to be conducted with commercial (or near-commercial) material in the PNW sweet cherry breeding program. Ideally, a breeding program screen would identify canker-resistant elite parents that can be used in crosses targeting canker resistance and commercial fruit quality. Breeding program parents and selections can also be used to validate DNA tests for resistance factors identified in the USDA-ARS collection. Once validated, these tests could then be used to further screen seedlings for resistance. For powdery mildew, it is confirmed that there is a presence of 3 resistance factors (Pmr1a, Pmr1b1, and Pmr1b2). The current DNA test can detect these factors but cannot distinguish all three of them from each other. A refinement of the DNA test for powdery mildew resistance currently used by the breeding program would allow all these alleles to be distinguished from one another, and potentially combined to maximize durability of resistance.
Objectives:
- Identify genetic factors for bacterial canker resistance (Year 1).
- Identify critical DNA sequence differences in the 3 confirmed powdery mildew resistance factors (alleles) of Pmr1 (Year 1).
- Collect robust phenotypic data for bacterial canker and powdery mildew resistance on Breeding Program parents and selections (Year 1 and 2).
- Confirm what resistance levels are in the Breeding Program (Pseudomonas).
- Generate critical data for non-genotyped parents and selections (Pseudomonas and powdery mildew).
- Develop new or refined DNA tests for screening for PM and Pseudomonas (Year 2).
- Genetically characterize Breeding Program parents/selections with new tests.
Project Title: Cherry Rootstock Research and Demonstration Orchard
Organization (s): Washington State University
Principal Investigators (s): Sallato, B., Whiting, M.
Total Funding Amount for All Years: $74,292
Length: 3 Years
Sweet cherry rootstocks affect multiple and fundamental aspects of producing high quality sweet cherries, from tree size, fruit yield and quality, precocity, to environmental responses, such as frost, drought, heat, and disease tolerance. Thus, the selection of appropriate rootstocks is crucial for optimizing sweet cherry productivity and quality, and long-term resilience to environmental stressors. The next generation of Washington’s cherry orchards need to become more productive with high quality fruit while facing increasingly variable weather conditions. In the last five seasons, many growers in Eastern Washington have lost entire crops due to frost damage, heat waves, and summer rain; threats associated with more frequent and unpredictable weather events. There are new rootstock genotypes that claim to have improved stress tolerance, as well as precocity. Some of these rootstocks include A9 x VSL2, Rulan 8, Krymsk 7, EC 11, EC 12 and RVL 4, that will soon be available for Washington and Oregon sweet cherry growers. The adaptation of a particular rootstock is influenced by multiple growing factors; thus, it is difficult to extrapolate results among regions. There is no public rootstock demonstration and research orchard that can provide systematic evaluation side by side. The researchers on this project plan to establish a new rootstock evaluation block at the Washington State University headquarters farm (IAREC).
The aim is to develop a systematic and contrasting evaluation of new cherry rootstocks for Washington and Oregon growers and includes the following objectives:
- Establish a public sweet cherry rootstock research and demonstration orchard in Prosser.
- Evaluate key horticultural traits imposed by different rootstocks including precocity, bloom timing, yield, and fruit quality.
- Evaluate adaptation to environmental threats provided by new rootstocks, including heat, drought, and frost tolerance.
- Deliver information to Washington and Oregon growers.
Project Title: A Robust PNW Sweet Cherry Breeding and Genetics Program
Organization (s): Washington State University, Oregon State University
Principal Investigators (s): McCord, P., Galimba, K., Peace, C.
Total Funding Amount for All Years: $743,445
Length: 3 Years
The sweet cherry breeding and genetics program in Prosser, WA, serves as an important source of sweet cherry varieties for the Pacific Northwest. Since the re-launch of the program in 2018, significant infrastructure improvements have been made, and a series of promising new selections is advancing through the breeding pipeline. Infrastructure improvements have included remodeling the molecular laboratory, sterile flow hoods for embryo rescue, re-wiring the seedling greenhouse, the construction of a 30 x 96-foot hoop house for crossing, and a state-of-the art optical fruit sorter. Seeds produced are almost exclusively from bi-parental crosses targeting industry-relevant traits, and embryo rescue has been successfully implemented for crosses targeting early ripening. More than 7,000 new seedlings have been planted over the past five years, with pre-selection guided by an ever-growing number of DNA tests. Eleven new selections have been planted in replicated and randomized Phase 2 trials at Prosser, Pasco, Naches, and Hood River. Three selections (R3, R19 and R29) have been advanced to on-farm Phase 3 trials for pre-commercial evaluation. R3 and R19 (both early ripening dark sweet varieties) are nearing the end of their Phase 3 evaluation and are expected to be released in the next 12-15 months, with tree sales as early as 2026 for R19, and 2027 or 2028 for R3. R19 in particular is a ‘Chelan’ replacement. The ultimate goal is that the breeding program can become self-sustaining via royalty income. The release and promotion of R3 and R19 will move the program toward that goal, as will the continued development of other promising selections currently in our pipeline.
Objectives:
- Rigorously evaluate seedlings and selections at all phases of the breeding program, including those now in Phase 3.
- Increase the quality of seedlings planted in the first phase of the breeding program.
- Continue to utilize DNA information for Superior and Complementary parent selection and seedling screening.
- Deploy newly developed DNA tests for fruit size.
- Increase seed germination rates to allow for more stringent DNA-based selection for priority traits.
- Maintain or improve the overall health of breeding program orchards via continued screening for viruses and phytoplasma.
- Continue to implement timely and proper practices for orchard management (training/pruning, pest and disease monitoring and control, irrigation and nutrient management.)
Project Title: Evaluating Heat Stress Response in Novel Cherry Rootstocks
Organization (s): Oregon State University
Principal Investigators (s): Thompson, A., Galimba, K., Pearson, B.
Total Funding Amount for All Years: $111,220
Length: 3 Years
Recent increases in summer temperatures are of great concern to the sweet cherry industry throughout the Pacific Northwest. The 2021 Pacific Northwest heat dome caused temperatures in The Dalles, OR to soar to 118°F and similar record setting temperatures were recorded across the cherry growing regions of Washington. A 2024 survey conducted in Wasco County, OR identified new cherry rootstock research as a high priority for the region with 73% of participants in support. Heat and water stress resistance was identified as the most critical characteristics to be considered given recent increased summer temperatures within the Pacific Northwest. In our changing climate, it is critically important to measure and evaluate environmental stress responses of new cherry rootstocks on plant development, growth, and fruit production to ensure stakeholders are investing in plant material that will continue to be viable for the future. There are several new rootstocks that have been released recently, including but not limited to: A9 x VSL2, Rulan 8, Krymsk 7, EC 11, EC 12 and RVL 4. These rootstocks will be commercially available soon; however, little is known about their growth performance characteristics and response to expected environmental stressors, especially when compared to conventional rootstocks such as Mazzard, Krymsk 5 and Gisela 12. Empirical research is critical to aid in selection of new rootstocks that are resilient to environmental stress. As climate data research suggests, this will become increasingly important for success of orchards in the Pacific Northwestern U.S. as high heat events are expected to occur more frequency. The team plan on grafting these eight rootstocks with the self-fertile, stress-sensitive variety ‘Skeena’ to better understand their heat stress tolerance and horticultural traits.
Objectives:
- Quantify stomatal conductance, leaf temperature, and chlorophyll fluorescence heat tolerance of the heat sensitive variety ‘Skeena’ grafted on to A9 x VSL2, Rulan 8, Krymsk 7, EC 11, EC 12 and RVL 4, Krymsk 5, Mazzard, and Gisela 12 to understand how new rootstocks respond to environmental conditions in a region where heat stress is common. In addition, through the measurement of stomatal conductance in conjunction with quantified evapotranspiration and plant available water of soil within irrigated rows, the ability to determine how irrigation management practices influence stomatal conductance, plant growth, and fruit development.
- Assess horticultural traits, including tree growth (as trunk cross sectional area), yield, flower counts.
- Measure fruit quality (size, firmness, stem retention, sugars, color, and surface pitting) at harvest and following three weeks of cold storage.
Contact:
Paige Beuhler (Administrative Officer): paigeb@treefruitresearch.com, 509 665 8271 ext. 2
Ines Hanrahan (Executive Director): hanrahan@treefruitresearch.com; 509 669 0267
