Tree habit and productivity.

The tree of ‘Harovin Sundown’ is medium in size, conical and upright to spreading, annually productive, and winter-hardy, producing a good crop after exposure to winter minimum temperatures as low as –29 °C. There has been no evidence of biennial bearing. Precocity of ‘Harovin Sundown’ on standard (Bartlett seedling) rootstock appears to be similar to that of ‘Bartlett’ with trees coming into production ≈4 years after planting. Annual yields of harvested fruits have been equal to or greater than those of ‘Bartlett’, especially in areas where fire blight has adversely affected the productivity of ‘Bartlett’.

Shoot habit.

The bark on the sun-exposed side of dormant shoots is orange–brown [RHS code 175A or 175B; Royal Horticultural Society (RHS), 1966]. After the 2006 growing season, the internode length (mean ± se, n = 200) of ‘Harovin Sundown’ was 38.2 ± 0.4 mm as compared with that of ‘Bartlett’ (32.7 ± 0.3 mm), ‘Harrow Sweet’ (29.1 ± 0.4 mm), ‘AC Harrow Crisp’ (32.6 ± 0.4 mm), and ‘Beurré Bosc’ (46.0 ± 0.6 mm).

Leaves.

Leaves of ‘Harovin Sundown’ are elliptic, the shape of the base of the leaf blade is right-angled, and the shape of the upper part of the leaf blade is right-angled with pointed or broad acuminate tips. There is little curvature of the midrib. Leaf serrations are small and shallow but distinct. The angle between the petiole and the shoot is less than 30°, the petiole is medium in length (mean ≈24 mm, range, 15 to 32 mm), and stipules are sometimes absent. The attitude of the leaf in relation to the shoot is outward (i.e., leaves are predominantly horizontal on vertical shoots rather than pointing upward or downward). Actively growing shoot tips are reddish green with light pubescence.

Fire blight tolerance.

Like with other introductions from the AAFC pear breeding program formerly located at Harrow (Hunter et al., 1992, 2002a, 2002b; Quamme and Spearman, 1983), ‘Harovin Sundown’ has excellent resistance to fire blight (caused by E. amylovora), similar to or greater than that of ‘Kieffer’, which is used as the standard for selection (Hunter, 1993). Using natural fire blight infection scores (from van der Zwet et al., 1970), ‘Harovin Sundown’ had a resistance rating much greater than that of ‘Bartlett’ (Table 1). When actively growing shoot tips were inoculated with a mixture of six virulent strains of E. amylovora, the length of the lesion that developed extended to ≈12% of the current season's growth, similar to ‘AC Harrow Crisp’ and ‘Harrow Sweet’, but less than ‘Kieffer’ and much less than lesion development in ‘Bartlett’ (Table 1). Similar results have been obtained in greenhouse studies using young grafted trees (data not presented), suggesting that rootstock has little impact on relative susceptibility to this pathogen.

Table 1.

Summary of fire blight evaluations of ‘Harovin Sundown’ at AAFC, Harrow, Ontario, Canada.

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Bloom and pollination.

First bloom and full bloom of ‘Harovin Sundown’ are both ≈2 d later than ‘Bartlett’, and this attribute may lead to less blossom damage caused by spring frosts. Flower clusters typically contain seven flowers, occasionally six or eight, rarely five or nine. Petals are white, broad ovate, and are slightly apart to just touching with no overlap. When the flower is just opening, anthers are pink to dark pink (RHS code 51A, 58A, 58B), but anther color changes rapidly once the flower opens. Anthers are large in size and are level with or slightly above the stigma when the flower is fully open.

Pollen compatibility has been assessed using pollination records from the breeding program and from a limited number of crosses made specifically for this purpose using methods described earlier (Hunter et al., 2002a, 2002b). Generally, a fruit set of greater than 20% is required for commercial fruit production, whereas fruit set less than 10% suggests incompatibility. Results have been inconsistent over the years, and, in some cases, fruit set has varied widely from year to year. ‘Harovin Sundown’ has successfully pollinated ‘Beurré d'Anjou’, ‘Bartlett’, ‘Beurré Bosc’, ‘Clapps Favorite’, ‘Flemish Beauty’, ‘AC Harrow Crisp’, ‘AC Harrow Gold’, and ‘Swiss Bartlett’. Cultivars that have successfully pollinated ‘Harovin Sundown’ include ‘Beurré Bosc’, ‘AC Harrow Crisp’, ‘AC Harrow Gold’, and ‘Swiss Bartlett’, whereas ‘Bartlett’ pollen does not consistently produce adequate fruit set for commercial production. There is also some evidence from controlled pollination trials for self-compatibility in ‘Harovin Sundown’. Fruit production in commercial trial orchards planted to ‘Bartlett’, ‘AC Harrow Crisp’, ‘AC Harrow Gold’, ‘Swiss Bartlett’, ‘Harovin Sundown’, and HW620 (a selection currently undergoing advanced testing) has equaled or exceeded provincial averages for all cultivars, indicating that this combination of cultivars allows for adequate crosspollination under Ontario, Canada, conditions.

‘Harovin Sundown’ tends to produce secondary flower clusters, which can lead to the development of a late-ripening second crop. Secondary flowering has not resulted in increased fire blight infections.

Shape and color.

Fruit are symmetrical and ovate–pyriform to turbinate in shape (Fig. 2). In profile, the fruit shape is convex to almost straight and has been rated mostly as 3.3 and 5.3 using International Board for Plant Genetic Resources (IBPGR) descriptors (Thibault et al., 1983); individual fruits have received IBPGR ratings (listed in decreasing order of frequency) of 3.3, 5.3, 1.3, 3.1, 5.1, and 7.1. The calyx is persistent at harvest with short to medium length sepals that are convergent to upright. Based on visual estimates, the calyx basin is medium depth, medium to broad in width, and the margin is slightly ribbed. When harvested, fruits are green with a red blush on the sun-exposed fruit surface. After ripening at ≈20 °C, the skin develops a very attractive golden yellow ground color (RHS code 11A or 11B), whereas the blush on sun-exposed fruit surfaces becomes more orange than red. The skin is very smooth and there is no russeting of the fruit. The flesh is white to cream white in color (RHS code 158A or 158B), very fine in texture, grit-free, and becomes buttery and very juicy when fully ripe. The fruit has a strong intense pear flavor. Core breakdown has not been a problem with this cultivar.

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Fruit of ‘Harovin Sundown’ pear.

Citation: HortScience horts 44, 5; 10.21273/HORTSCI.44.5.1461

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Yields and fruit size.

In a commercial orchard planted in 1999 in Niagara Region, Ontario, the first harvest of commercial yield of ‘Harovin Sundown’ occurred in 2003, the same year as ‘Bartlett’ in the same orchard (Table 2). Annual production of ‘Harovin Sundown’ increased during the first 5 production years, and the cumulative yield of ‘Harovin Sundown’ was ≈14% greater than that of ‘Bartlett’. In this commercial orchard, mean fruit weights for ‘Harovin Sundown’ and ‘Bartlett’ were ≈231 g and ≈135 g, respectively (Slingerland, unpublished data). Fruits of ‘Harovin Sundown’ are similar in size or slightly larger than those of ‘Bartlett’ on unthinned trees, but when thinned to two fruits per cluster according to Ontario recommendations for fresh market pear production (Ontario Ministry of Agriculture, Food and Rural Affairs, 2006), very large fruits, some greater than 76 mm in diameter, were produced. The fruit size distribution for thinned trees showed that for ‘Harovin Sundown’, ≈56% of the fruit weight and ≈43% of fruit numbers were in the greater than 70 mm classes, whereas the corresponding values for ‘Bartlett’ were ≈19% and ≈14% (Table 3).

Table 2.

Harvested fruit yields (t·ha⁻¹) of ‘Harovin Sundown’ at St. Davids, Ontario, Canada, 2003–2007.^z

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Table 3.

Fruit size distribution of ‘Harovin Sundown’ at AAFC, Jordan Station, Ontario, Canada in 2008.

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Maturity.

At Harrow, the fruit of ‘Harovin Sundown’ mature in mid-September, ≈3 weeks after ‘Bartlett’ and just before ‘Harrow Sweet’ (Table 4). At Vineland, ‘Bartlett’ was picked ≈1 Sept. and both ‘Harovin Sundown’ and ‘Harrow Sweet’ were harvested ≈22 Sept., a few days later than at Harrow.

Table 4.

Harvest date and fresh fruit evaluations for ‘Harovin Sundown’ at AAFC, Harrow, Ontario, Canada.

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Quality and storage.

Fruits were harvested each year at the normal level of maturity for commercial harvest of fruits for the fresh market (5 to 7 kg pressure). Samples of five to 10 fruits selected at random were ripened at ≈20 °C immediately after harvest and after 4 weeks in common cold storage at ≈2 °C. Evaluations were made on appearance, flavor, texture, number, and size of grit (stone cells) in the flesh, juiciness, and core size relative to fruit size. At Harrow, trained panelists rated the appearance of ripened fruit of ‘Harovin Sundown’ as very good, similar to ‘Bartlett, but with a lower score than ‘AC Harrow Crisp’ (Table 4). The fresh fruit quality, as indicated by the weighted score, of ‘Harovin Sundown’ was lower than ‘Bartlett’ and ‘AC Harrow Crisp’ (Table 4). Panelists sometimes reported an astringency associated with the skin of pears ripened shortly after picking, but this astringency was absent or not reported when fruits were ripened after ≈3 to 4 weeks in common cold storage at ≈2 °C. Fruits of ‘Harovin Sundown’ held in common cold storage at ≈2 °C until early to mid-January and then ripened for 2 to 3 d at room temperature have received acceptable ratings for appearance, flavor, and texture, whereas the quality of ‘Bartlett’ fruits start to decline by November (data not presented).

Processing evaluations.

When ripened fruit were processed as pear halves, ‘Harovin Sundown’ was inferior to ‘Bartlett’ in appearance, flavor, and texture (data not presented). Because of the large fruit size, fewer pear halves fit into a can, so it was difficult to obtain the legally required weight for that can size. Recovery was adequate when processed as a diced product. When processed as pear puree, ‘Bartlett’ was rated significantly better than both ‘Harovin Sundown’ and ‘AC Harrow Crisp’. Although the processed product from small-scale trials was rated good, the quality was not sufficiently high for ‘Harovin Sundown’ to have commercial acceptability for processing as halves or puree.