‘Sunrise’ is an early-maturing pear cultivar that combines excellent appearance and fruit quality and good storage potential for an early-maturing pear with resistance to fire blight caused by the bacterium Erwinia amylovora (Burr.) Winsl. et al. (van der Zwet and Beer, 1999). All major cultivars of commercial importance as well as many of those grown by home orchardists are susceptible to this devastating disease, which is endemic to most pear production areas of the northern hemisphere. ‘Sunrise’ was released by the U.S. Department of Agriculture in 2006.
Origin
The original seedling tree of ‘Sunrise’ originated from a cross of NJ5001710820 × US 446 (Fig. 1) performed in 1965 by H.J. Brooks soon after he revived the USDA pear breeding program initiated by Merton Waite in 1908 (Magness, 1937). It was tested as OHUS 66170-047 and was selected in 1977 from the seedling orchard at the Ohio Agricultural Research and Development Center in Wooster, OH by R.C. Blake and T. van der Zwet. ‘Sunrise’ is composed of Pyrus communis L. and Pyrus pyrifolia (Burm.) Nakai parentage. The sources of fire blight resistance are the P. communis cultivar Seckel and the P. pyrifolia selection New Jersey 1. Subsequently, ‘Sunrise’ has been evaluated for fruit quality, fire blight resistance, and productivity in replicated trials of clonally propagated trees at the USDA-ARS Henry A. Wallace Beltsville Agricultural Research Center in Beltsville, MD, the Ohio Agricultural Research and Development Center in Wooster, OH, and the Appalachian Fruit Research Station in Kearneysville, WV. It is currently being tested or has been tested at eight experiment stations throughout the United States for range of adaptation and productivity under a variety of environmental conditions and management systems.
Description
Fruit traits.
The fruit of ‘Sunrise’ (Fig. 2) are obviate–acute–pyriform to oblong–pyriform in shape (Zielinski, 1955), equivalent to the International Board for Plant Genetic Resource shape ratings of 5.2 and 7.2, respectively (Thibault et al., 1983). Fruit diameter was similar to ‘Bartlett’ but less than ‘Clapp's Favorite’ (Table 1), whereas length was similar to ‘Clapp's Favorite’ and greater than ‘Bartlett’. The core is slightly smaller than ‘Bartlett’ and ‘Clapp's Favorite’. Skin color at harvest is light green, and most fruits (≈67%) are blushed with 2% to 50% of the surface with red or pink color. The skin turns yellow (Royal Horticultural Society Color Chart codes 2B, 2C, and 3B) when ripe (Royal Horticultural Society Enterprises Limited, 2001). The finish is glossy and the skin surface is smooth with a regular contour. The cavity is acute or lipped, and the basin is typically medium in depth and abrupt. The stem is typically moderately long, averaging 29.5 mm, smooth or fleshy, especially next to the cavity, oblique or upright, and averages 3.6 mm in thickness, similar to ‘Bartlett’ (3.2 mm) but less than ‘Clapp's Favorite’ (6.3 mm). Skin russeting is intermediate between ‘Bartlett’ and ‘Clapp's Favorite’ with most russeting being in the form of slightly prominent lenticel corking and occasional splotches of smooth tan russet. Overall appearance rated as well as ‘Bartlett’ and ‘Clapp's Favorite’. Flesh is creamy white, buttery, moderately fine in texture, and moderately juicy, similar to ‘Bartlett’. Grit content and size are light, similar to or better than ‘Bartlett’ and ‘Clapp's Favorite’, uniform in distribution and size throughout the flesh and under the skin. Flavor is sweet to subacid, being slightly less acidic than ‘Bartlett’ and ‘Clapp's Favorite’, and lightly aromatic, slightly less so than ‘Bartlett’ but more so than ‘Clapp's Favorite’. Consumer ratings of flavor, appearance, and overall quality have been comparable to or higher than ‘Bartlett’, ‘Conference’, and other cultivars (Elkins et al., 2008).
Quantitative descriptive and sensory traits of ‘Sunrise’, ‘Bartlett’, and ‘Clapp's Favorite’.z
Optimum harvest maturity, determined by fruit quality and storage life, occurs ≈2 weeks before ‘Bartlett’ during the first week of August at Kearneysville, WV, just after ‘Butirra Precocé Morettini’ and slightly before ‘Clapp's Favorite’. When harvested at this time, storage life without breakdown or superficial scald in air at –1 °C is ≈3 months, better than ‘Bartlett’ and ‘Clapp's Favorite’. Ripening to eating firmness requires a mean of 8 d, similar to ‘Bartlett’ and ‘Clapp's Favorite’, and it does not require prolonged cold storage to induce the climacteric.
Tree and fruiting habit and productivity.
The trees are moderately vigorous on ‘Bartlett’ seedling and OH×F97 rootstock and upright-spreading in growth habit. Fruit are borne primarily on spurs, but also on terminal buds of terminals and lateral shoots. Clusters of two or three fruit are not uncommon, but thinning requirements have not been investigated. Average date of first bloom is 2 d before ‘Bartlett’, similar to ‘Beurré Anjou’. In a replicated and randomized yield trial, precocity and production were similar to ‘Bartlett’ as was mean fruit weight (Table 2). The planting from which productivity and fruit size data were collected was lightly to moderately pruned annually, fertilized according to commercial recommendations, and insect and diseases were managed according to local extension service recommendations. Mean fruit size in other plantings has been larger; fruit from which firmness data were collected averaged 219 g (n = 205) with a maximum of 376 g. ‘Bartlett’ averaged 194 g (n = 95) with a maximum of 336 g, and ‘Clapp's Favorite’ had a mean of 203 g (n = 84) and a maximum of 332 g.
Mean yearly and cumulative yield in kg per tree for ‘Sunrise’ and ‘Bartlett’.z
Controlled pollination experiments indicated that ‘Sunrise’ is cross-compatible with ‘Bartlett’, ‘Beurré Bosc’, and ‘Beurré Anjou’. Bloom would overlap that of all three of these cultivars.
Chilling requirement.
Chilling requirement has not been determined, but trees have been grown and fruited normally as far south as Clemson, SC, where the number of chilling hours (0 to 7.2 °C) averages ≈800.
Disease and insect resistance.
Observation of response to natural infection indicated that ‘Sunrise’ is very resistant but not immune to fire blight, comparable to ‘Potomac’ (Table 3). Response to artificial infection also indicated that ‘Sunrise’ is significantly more resistant than ‘Bartlett’ and as resistant as ‘Potomac’ (Table 4). Blossom infection of ‘Sunrise’ was compared with that of ‘Bartlett’ as a susceptible control and ‘Old Home’ as a resistant control. The percentage of blossoms of ‘Sunrise’ infected after artificial fire blight inoculation was high and similar to ‘Bartlett’ (Table 5). ‘Old Home’, which is highly resistant to shoot infection, was also susceptible to blossom infection. However, the severity of blossom infection of ‘Sunrise’ was less than that of both ‘Bartlett’ and ‘Old Home’ as shown by the significantly lower mean severity score for each cluster and the lower percentage of infected spurs and older wood. However, for those branches that did become infected, mean lesion length for ‘Sunrise’ was intermediate between the susceptible and resistant controls. At a mean lesion length of 262 mm, the potential for significant spread of infection of older fruit-bearing branches appears greater than that suggested by the shoot tip inoculations.
Response to epiphytotic fire blight infection.z
Response to artificial shoot infection in 2 years.z
Response to artificial fire blight inoculation of blossoms.z
Observations indicate that the cultivar is moderately resistant, but not immune, to pear scab (Venturia pirina Aderh.). ‘Sunrise’ is susceptible to powdery mildew [Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon] and Fabraea leaf spot [Diplocarpon mespili (Sorauer) Sutton]; however, fruit infection by Fabraea leaf spot is minimal. ‘Sunrise’ is susceptible to pear psylla (Cacopsylla pyricola Föerster) and control measures are necessary. Observations indicated that fruit of ‘Sunrise’ are also susceptible to damage by codling moth [Cydia pomonella (L.)], European pear sawfly (Hoplocampus brevis Klug), and brown marmorated stinkbug [Halyomorpha halys (Ståhl)].
Availability
Budwood of ‘Sunrise’ is limited and trees are not available from the U.S. Dept. of Agriculture. Interested nurseries and researchers should send requests for noncertified budwood to R.L. Bell. Pathogen-free certified budwood will be available from the National Clean Plant Network–Fruit Trees. Genetic material of this release will be deposited in the National Plant Germplasm System, where it will be available for research purposes, including development and commercialization of new cultivars. It is requested that appropriate recognition be made if this germplasm contributes to the development of a new breeding line or cultivar.
Literature Cited
Bell, R.L., van der Zwet, T., Blake, R.C., Chandler, C.K. & Scheerens, J.C. 1996 ‘Potomac’ pear HortScience 31 884 886
Elkins, R.B., Turner, J., Seavert, C.F., Castagnoli, S., Mitcham, E.J., Biassi, S.V., Colonna, A. & Bell, R.L. 2008 Evaluation of potential alternative European pear cultivars for U.S. west coast growers Acta Hort. 800 483 490
Littell, R.C., Milliken, G.A., Stroup, W.W. & Wolfinger, R.D. 1996 SAS® System for mixed models SAS Institute, Inc Cary, NC
Magness, J.R. 1937 Breeding apples and pears U.S. Dept. Agr. Ybk. 575 630
Norelli, J.L., Aldwinckle, H.S. & Beer, S.V. 1988 Virulence of Erwinia amylovora strains to Malus sp. Novole plants grown in vitro and in the greenhouse Phytopathology 78 1292 1297
Royal Horticultural Enterprises Limited 2001 Royal Horticultural Society colour chart Royal Horticultural Enterprises Limited Woking, Surrey, UK
SAS Institute 1990a SAS procedures guide, Version 6 3rd Ed SAS Inst Cary, NC
SAS Institute 1990b SAS/STAT user's guide, Version 6 4th Ed Vol. 1 SAS Inst Cary, NC
SAS Institute 1990c SAS/STAT user's guide, Version 6 4th Ed Vol. 2 SAS Inst Cary, NC
Thibault B., Watkins R. & Smith R.A. 1983 Descriptor list for pears (Pyrus) Intl. Board Plant Genet Resources, Rome, Italy
van der Zwet, T. & Beer, S.V. 1999 Fire blight—Its nature, prevention, and control: A practical guide to integrated disease management U.S. Dept. Agr., Agr. Inform. Bul. No. 631
van der Zwet, T., Oitto, W.A. & Brooks, H.J. 1970 Scoring system for rating the severity of fire blight in pear Plant Dis. Rptr. 54 835 839
Zielinski, Q.B. 1955 Modern systematic pomology W.C. Brown Dubuque, IA
