'US Furr' and 'US Furr-ST' Mandarins

Abstract

This document marks the official release of 'US Furr', a hybrid of 'Clementine' × 'Murcott', and 'US Furr-ST', an irradiated variant of 'US Furr' with apparent field tolerance to citrus scab (causal agent Elsinoe fawcettiBitanc. and Jenk.). The hybridization creating 'US Furr' and ultimately 'US Furr-ST' was made at the USDA Horticultural Research Laboratory in Orlando, Florida, by Dr. Phillip Reece in 1953. Seeds were sent to the USDA Date and Citrus Station in Indio, California for hybrid evaluation. Dr. Joseph Furr identified this superior selection from the resulting seedlings. 'US Furr' has been sufficiently promising that it has been introduced into at least five countries, under several different names. Budwood of 'US Furr' was introduced into Argentina, Brazil, France (Corsica), Israel, and Spain in the 1980s and 1990s using material prior to irradiation and some possibly post-irradiation. 'US Furr' and 'US Furr-ST' are high quality, December/January-maturing mandarins with excellent rind color, superior flavor, and moderate peelability (rind comes off in pieces similar to 'Sunburst' and 'Murcott'). 'US Furr' and 'US Furr-ST' are sexually self-compatible and fruit in mixed plantings average 12 to 24 highly polyembryonic seeds per fruit, and 6 to 12 seeds per fruit when planted in isolation from compatible pollinating varieties. Furthermore, very few to no fruit are set when flowers are bagged, indicative of low parthenocarpy. 'US Furr' and 'US Furr-ST' fruit average 150-215 g per fruit at maturity. 'US Furr' and 'US Furr-ST' trees are moderately vigorous, thornless, and spreading with fairly dense foliage. The diversity of names used for 'US Furr' / 'US Furr-ST' has reduced awareness that a single genotype has garnered wide attention, limiting impact and resulting in few US plantings. It is anticipated that this official release will garner increased interest in these cultivars leading to increased plantings. Many tasters report that 'US Furr' and 'US Furr-ST' are among the best tasting citrus they have eaten. These mandarin cultivars merit consideration for planting as a part of a mid-late season mandarin portfolio, and are released without any intellectual property restrictions.