Interest in growing olives, a high-value specialty crop, is increasing in Oregon. However, research-based information about cultivar selection and other production practices for growing olives in the state is lacking. The primary challenges are damage to the trees from low winter temperatures and a relative lack of growing degree days to ripen fruit.
Most olives are produced in warmer, mild-winter climates, and there is a need for information on the resistance to winter damage of various olive cultivars. Identifying cultivars that are sufficiently cold-resistant and produce quality fruit in Oregon’s shorter ripening season is essential. Additionally, growing techniques must be refined to adapt to the state’s climactic conditions.
In response, Oregon State University, with strong support from Oregon’s fledgling olive industry, initiated the Olea: Olive Research for Oregon project. The goal is to grow as many olive cultivars as possible in a field evaluation and to select cultivars best adapted to the region.
To address the challenges, cultivars from the U.S. Department of Agriculture Germplasm Repository in Davis, California, were obtained as cuttings or small plants. Hundreds of cuttings were propagated for a replicated, multi-year field evaluation at the OSU North Willamette Research and Extension Center (NWREC) in Aurora.
By July 2021, a 1-acre field was prepared with weed mat and drip irrigation, on which 116 cultivars, replicated four times if available, totaling 420 plants, were planted. The plot was irrigated during the warm summer months and lightly fertilized in early August. Data collection each year has included measuring plant growth, flowering, fruit set, yield, fruit maturation and size as well as cold injury. Information has been shared with industry stakeholders, growers and the public through tours, visits, classes and media.
In 2024, a survey was launched to collect data about olive producers to better understand their needs and the industry’s status. The Olea project participated in various meetings, including a poster presentation at the International Olive Sustainability Conference in Davis. An Olive Field Day was held at NWREC in May with record attendance. Evaluations from the event were overwhelmingly positive, with 100% of respondents indicating they learned something applicable to their olive operations.
Significant collaborations were initiated in 2024, including working with Wright State University in Ohio to determine the susceptibility of olives to the invasive emerald ash borer — which was detected in Oregon in 2022 — and partnering with the OSU Southern Oregon Research and Extension Center in Central Point to explore olives as a potential future commodity in that region.
Additionally, the Olea project team traveled to Seville, Spain, to collaborate with researchers at the Instituto de la Grasa and the Cordoba Germplasm Repository. The project continues to receive strong industry support and aims to make olive production in Oregon a successful endeavor.
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