Trialing apricots in Riverside, California: Identifying cultivars suitable for culture in a low-chill environment

Authors: Ledbetter, Craig; Krueger, Robert

Submitted to: Advances in Plants and Agriculture Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2017
Publication Date: 12/15/2017
Citation: Ledbetter, C.A., Krueger, R. 2017. Trialing apricots in Riverside, California: Identifying cultivars suitable for culture in a low-chill environment. Advances in Plants and Agriculture Journal. 7(6):281-287.

Interpretive Summary: Apricot is enjoyed by many consumers, but the tree is not widely adapted to climatic conditions around the country. It is grown primarily in the San Joaquin Valley, with production now centered near Patterson, California. Apricot varieties vary in chilling requirement, and there are production problems when trees are grown in areas that receive inadequate chilling. For several million Southern California consumers, there are currently no recommendations for apricots capable of growing and producing fruit in that region. Because of this lack of information, an apricot variety trial was established in Riverside, California where chill hour accumulation is approximately 1/3 of that received near Patterson, California. Bloom strength and fruit production potential of six diverse apricot varieties were scored over the course of four harvest seasons. Five of the six apricot varieties performed poorly at the low-chill site, expressing irregular vegetative bud break and pre-bloom floral bud shedding that led to poor fruit production. The Blenheim variety, however, remained productive throughout the study, producing full crops even after dormant periods with as few as 161 chill hours. This information is important to Southern California consumers with interest in apricot production. The Blenheim variety can be recommended to these consumers for planting at low-chill sites.

Technical Abstract: Six apricot cultivars were evaluated for cropping performance in the low-chill environment of Riverside, CA during four crop seasons (2012 through 2015). Trialed apricots were currently used commercial cultivars that ranged widely in bloom date. Chill accumulations at the Riverside site ranged from 161 h to 470 h during the study, providing opportunities to evaluate performance under sub-optimal chill conditions. In general, the trialed apricots were not well adapted to the Riverside environment. Irregular budbreak and pre-bloom floral bud shed were symptoms common to five of the six trialed cultivars. Cultivar Blenheim was the exception, producing crop loads that required thinning even after a dormant season with only 161 chill hours. Bloom duration (first to full) for ‘Blenheim’ averaged 34 d in the Riverside plot, leading to a similarly lengthy fruit maturation period. Of the six trialed apricots, only cultivar Blenheim can be recommended for non-commercial planting in environments having chill accumulations similar to Riverside, CA.