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Yan-xin Duan, Ying Xu, Ran Wang, and Chun-hui Ma

‘Akizuki’ ( Pyrus pyrifolia Nakai), a Japanese pear, plays an important role in pear production in China because of its good quality characteristics such as large fruit, pretty shape, delicate pulp. and high soluble solid content. However, with the

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Richard L. Bell

Pear psyllids [ Cacopsylla pyri (L.), C. pyricola (Förster), and C. pyrisuga (Förster)] are major arthropod pests of pear ( Pyrus communis L.) throughout North America and Europe. Both adults and nymphs feed primarily in the vascular tissue of

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Maojun Zhang, Lihua Ding, Qiang Wang, Meiqi Feng, and Shahrokh Khanizadeh

Province and was released in 2003 by one of the authors (MZ). Fig. 1. Pedigree of ‘Hanhong’ pear. The name ‘Hanhong’ makes reference to two characteristics: “very hardy and red skin colour on the surface exposed to the sun.” ‘Nanguoli’ is a

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Javier Sanzol, Pilar Rallo, and María Herrero

Apples and pears are fruit crops particularly susceptible to cropping irregularities. A strong relationship has been observed between the effective pollination period (EPP) and the general cropping of the orchard. The EPP concept has also been proven to be a useful parameter to establish a relationship between the variation in the reproductive process and cropping behaviors. For apples and pears, a slow pollen tube growth has been shown to be the main limiting factor of the EPP in the traditional cooler temperate cultivation regions. However, while higher temperatures speed up the pollen tube growth, the expansion of these crops into warmer areas often results in failures of fruit set. Thus, with the aim to ascertain the main limiting factor responsible for fruit set failures in Mediterranean conditions we have evaluated the EPP for two consecutive years in `Agua de Aranjuez' pear, the main Spanish cultivar, by studying the stigmatic receptivity, pollen tube kinetics, and ovule development. Complete flower fertility was maintained for just 2 days after anthesis in both years. Pollen tube kinetics and ovule degeneration do not appear to limit flower receptivity. However, the stigmatic receptivity expressed as flowers with at least one receptive stigma, closely matches the duration of the EPP evaluated from fruit set experiments. This was consistent over the 2 years of experiments, in spite of the differences recorded in the EPP, suggesting that stigmatic receptivity is clearly the limiting factor of flower receptivity. This is the first report for stigmatic receptivity limiting the EPP in pears and suggests that stigmatic receptivity could be an important factor limiting pear flower receptivity and hence cropping performance under warmer conditions.

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R.L. Bell

Eight cultivars and wild seedlings of pear (Pyrus spp.) from Eastern Europe were evaluated for resistance to feeding by early instar pear psylla [Cacopsylla pyricola (Foerster)] in a 24-hour assay. All were compared to a susceptible control, `Bartlett' (P. communis L.), and to a moderately resistant control, NY10352 (P. communis × P. ussuriensis Maxim. BC hybrid). Three P. communis cultivars, Bartjarka (PI 483391), Lucele (PI 483402), and Kajzerka (PI 506387), and a wild seedling (PI 506381) of undetermined species, exhibited a high degree of host resistance, measured as reduced frequency of feeding and increased either mortality or movement off of the plants.

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Shuang Jiang, Haishan An, Xiaoqing Wang, Chunhui Shi, Jun Luo, and Yuanwen Teng

The genus Pyrus (pears) consists of important fruit trees, and ≈20 primary species are generally accepted by most taxonomists ( Challice and Westwood, 1973 ). Based on their geographic distribution, Pyrus species are divided into oriental and

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Murray Clayton, William V. Biasi, and Elizabeth J. Mitcham

We thank Michelle Lauer and David Bouck for their assistance. We acknowledge the California Pear Advisory Board for partial financial support. The cost of publishing this paper was defrayed in part by the payment of page charges. Under

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Mokhles A. Elsysy, Andrew Hubbard, and Todd C. Einhorn

Bloom and postbloom thinning is essential to managing yield and fruit quality in modern pear production systems. Much of the ‘Bartlett’ pear acreage in the western United States comprises well-established trees planted at low to medium density

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Thomas Sotiropoulos, Nikolaos Koutinas, and Anastasia Giannakoula

Naoussa is a late-July maturing pear ( Pyrus communis L.) cultivar originating from a cross between the pear cultivars Kristali and Coscia. Annual fruit production per tree of ‘Naoussa’ grafted on quince BA 29 rootstock over a period of 5 years

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Richard L. Bell and Tom van der Zwet

‘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