Pear cultivars

Introduction

This Factsheet provides information that will guide commercial growers in selecting fruit cultivars to plant. Recommendations for planting cultivars and adapted areas within the province have been determined by University of Guelph, Department of Plant Agriculture, Vineland, Agriculture and Agri-Food Canada (AAFC) and the Ontario Ministry of Agriculture and Food (OMAFRA). Valuable assistance was provided in consultation with growers, shipper/dealers, nurseries, processors and the Ontario Tender Fruit Producers' Marketing Board (OTFPMB).

The term "cultivar" is used throughout this Factsheet. Cultivar, a contraction of "cultivated variety," replaces the older and confusing term "variety," which also refers to recognizable types within a species that maintain their distinguishing characteristics in the wild state. A cultivar is any horticulturally recognized and named type or sort that can only be maintained through vegetative propagation or the use of selected breeding lines and seed sources.

Recommended Pear Cultivars

Recommended cultivars are listed in order of maturity in 3 groups in Table 1, "Recommended Pear Cultivars". Those listed under "General Planting" are mainly well known cultivars with proven performance and established market value. Cultivars listed under "Limited Planting" have value, but their planting generally should be limited for various reasons. Some may have proved valuable in previous trial plantings and now warrant limited commercial planting; others may have value only for special markets, such as early cultivars for roadside markets. The "Trial Planting" list identifies promising new releases from the AAFC breeding program formerly located at Harrow. For a more detailed description of pear cultivars, see section D, "Pear Cultivar Descriptions."

In Ontario, pears are grown in regions where winter temperatures may be severe enough to cause cold injury to shoots, fruit spurs, trunks and roots. Also, spring frost during bloom is a threat in most regions. To ensure fruiting, pears should be grown in areas that have some moderating affect from one of the Great Lakes or on a site with a slope that allows for good air drainage.

Table 1. Recommended Pear Cultivars

Pear Harvest Dates

Harvest dates are important to fruit growers, sales agents, processors and nurserymen. Table 2, "Average Date of First Harvest for Pear Cultivars", shows average dates of the first commercial harvest of pear cultivars at the University of Guelph, Department of Plant Agriculture, Vineland. These dates are averages of many years of observations. Only the most common cultivars or those of special interest are listed. Throughout the fruit growing districts of the province, actual harvest dates will differ from those reported at Vineland, and there may be minor variation in the sequence of cultivars harvested.

Table 2. Average date of first harvest for pear cultivars

Pear Pollination

Under Ontario conditions, commercial pear cultivars are considered self-unfruitful; consequently, cross-pollination with a suitable pollenizer cultivar is required. The pollenizer cultivar should bloom annually, flower at the same time as the cultivar to be pollinated and be cross compatible. Make sure those cultivars chosen as pollenizers are of commercial importance and suitable for the market requirements of the grower. Pollenizer cultivars should not be biennial in bearing habit or unusually susceptible to pests, disease or other problems that might interfere with the pollenizer function.

Most recommended pear cultivars flower at the same time and there is often satisfactory bloom overlap for effective cross-pollination among cultivars. The bloom season for pears, as for other fruit crops, varies among cultivars, from season to season and between locations. The long-term data collected at Vineland show an average full-bloom date of between May 15 and 17 among different cultivars. Full-bloom dates, however, are not useful for predicting the exact full-bloom period for this crop from year to year.

Cross-incompatibility (the inability of pollen from one cultivar to set fruit on another) is seldom found among diploid pear cultivars. The only exception of importance is the cross-incompatibility of Bartlett pollen with Seckel. There may be other causes of functional incompatibility among pear cultivars. The flowers of Bartlett and Bosc have abundant pollen and are satisfactory pollenizers of each other, as well as of other cultivars. Flemish Beauty has shown the highest degree of self-fertility among pear cultivars recommended in Ontario. Pollinated by Anjou, Flemish Beauty is a good pollenizer for Bartlett and Bosc.

In standard orchards, plant the pollenizer cultivar no more than 2 trees away from the main cultivar, i.e., at least 1 tree of a pollenizer cultivar for every 8 trees of the main cultivar. Because pear pollen grains are relatively large, little transfer of pollen by wind occurs. Honeybees, bumblebees and large flies are the major agents responsible for transferring pollen among pear cultivars. Two beehives per hectare in mature orchards are considered the minimum, and 4 hives/hectare are recommended for optimum pollination. Several hives can be placed together in a protected area. Research has shown that a great deal of pollen transfer does occur within the hive. Place the hives in the centre of every 2 ha by the time 10%-20% of blooms have opened. For best exposure to the sun, face hive openings south to stimulate early bee activity.

The nectar of pear flowers contains about 10% sugar as compared to the bloom of some weeds and fruit crops, which may contain up to 60% sugar in their nectar. For this reason, pear flowers are relatively unattractive to pollinating insects. Mow the orchard just prior to bloom to remove alternative nectar sources attractive to bees. Avoid orchard spraying during bloom and remove hives after bloom as soon as possible to avoid damage to bees from post-bloom sprays.

Bosc is an ideal pollenizer for Bartlett and is adequately pollinated by Bartlett as well. Anjou is a satisfactory pollenizer for Bartlett.

AC™ Harrow Crisp (formerly HW 610) tends to be a poor pollinator and will not consistently pollinate Bartlett, but Bartlett will pollinate AC™ Harrow Crisp to a limited extent. In pollination studies in 2000, good fruit set was obtained when AC™ Harrow Crisp was self-pollinated or pollinated by HW 614, with limited fruit set when pollinated by Bartlett. AC™ Harrow Crisp pollinated Bosc, Anjou, Flemish Beauty and AC™ Harrow Gold, with limited fruit set on Bartlett and Clapp's Favourite.

AC™ Harrow Gold (formerly HW 616)pollination of Bartlett has been variable. In some years, it does not appear to pollinate Bartlett, while in other years, good fruit set has been obtained with AC™ Harrow Gold pollen. In pollination studies in 2000, AC™ Harrow Gold pollinated Bartlett, Bosc, Anjou and Flemish Beauty. Bartlett does appear to consistently pollinate AC™ Harrow Gold. Bartlett, Bosc and AC™ Harrow Crisp pollinated AC™ Harrow Gold in recent pollination studies.

Pear Cultivar Descriptions

Brief descriptions are provided below for the major pear cultivars and those that show promise grown in Ontario. The descriptions are not intended to be complete but rather to indicate the general characteristics and performance of each cultivar in test plantings and/or commercial orchards in Ontario. Unless otherwise indicated, a cultivar is generally satisfactory in tree growth, hardiness, and cropping and fruit quality characteristics such as size, colour, shape and internal quality. These appraisals apply only to Ontario conditions. Performance elsewhere may be substantially different.

Pear Named Cultivars

Anjou

When well grown and properly handled, Anjou is a good quality dessert pear of long storage and shipping life. The skin is light green and, unlike Bartlett, does not change from green to yellow upon maturity. The flesh is very mild, aromatic and fine-textured. Lack of fruit-set is a common weakness of this cultivar. The tree is more fire blight resistant than the Bartlett cultivar. Anjou pear plantings in Ontario have decreased considerably since 1990 because the fruit's size and appearance has been only fair and has difficulty competing with other larger, cleaner pears.

Bartlett

This cultivar comprises about 75% of total pear production in North America. In Ontario, it is the leading cultivar by hectares and number of trees. Bartlett trees are productive and adaptable to a wide range of soils and climatic conditions. Careful orchard management is required to avoid fire blight and still obtain satisfactory yield and quality. Pick fruit at a pressure of 6.8-8.0 kg (15-19 lb) as measured on a pared surface of the fruit using a pressure tester with an 8 mm diameter tip plunger. Store fruit immediatelyat 1° C (30° F) until a week before it is used. Rapid removal of field heat and prompt cooling of harvested pears are associated with successful long-term storage. The maximum storage period for Bartlett at -1° C is about 2½-3 months.

In some years, abnormally cool temperatures 4-5 weeks prior to harvest have stimulated premature ripening of Bartlett pear. These pears soften, become yellow, and ripen at an accelerated rate. Do not store for a long period. Ripen Bartlett fruit at temperatures from 15-21° C (60-70° F). Maintain relative humidity in the storage and ripening rooms at about 90-95%.

Swiss Bartlett is a strain of Bartlett, which has similar tree and fruit characteristics.

A red budsport of Bartlett known as Max-Red Bartlett is also available. Max-Red is similar to Bartlett except for its red colour. It ripens one week after Bartlett.

Bosc

A high quality, flavourful, dessert winter pear with excellent keeping and shipping quality. Bosc is widely grown as a dessert pear in the western U.S. It is an important and well-adapted pear in milder regions of Ontario. The trees are very productive, come into bearing late and are susceptible to fire blight. They are difficult to train due to their leggy growth habit and lack of branching. A strain of Bosc from Oregon called OP-5 appears promising and warrants testing by growers in Ontario. In tests at Vineland, this strain has produced at an earlier age, and has an improved fruit shape and more uniform brown colour.

Clapp's Favorite

An attractive, large, productive, good quality pear maturing 2 weeks ahead of Bartlett. Pick fruit when they attain sufficient size, at least 10 days before full maturity. Failure to harvest fruit at the proper stage of maturity results in rapid core breakdown. The tree is vigorous, bears early and regularly, does well on heavy soils and is very cold hardy. It is susceptible to fire blight, however. Starkrimson is a brilliant solid red budsport of Clapp's. It has slightly tougher skin but is otherwise identical.

Flemish Beauty

The hardiest cultivar available for colder districts of Ontario. Flemish Beauty is susceptible to scale and fire blight. The tree is very productive and vigorous. The fruit are high in quality, but require careful timing of harvest to obtain full flavour and freedom from breakdown.

French Bartlett (Doctor Jules Guyot)

An old cultivar that was introduced to North America around 1885. Guyot resembles Bartlett in shape and colour, but tends to be larger and rougher. Trees come into bearing early, but breakage of branches is sometimes a problem. Guyot is not as good in quality as Bartlett but is quite acceptable. It ripens with or just after Clapp's Favorite.

Giffard

An early summer pear of good quality and medium size. When picked at the correct stage of maturity, it keeps well. It is suitable only for limited commercial planting as an early roadside and farm market cultivar.

AC™ Harrow Crisp (formerly HW 610) (Parentage: Bartlett x US56112-146)

It is a very attractive pear with red blush on smooth yellow skin. The cream-white flesh is smooth, grit-free and firm even when fully ripe, with a mild sweet flavour. The fruit matures at the end of Aug. or early Sept., about the same time as Bartlett. It can be picked over a 2-week period. Early picked fruit can be stored for about 2 months, but storage life is reduced with later picking. If kept too long or picked too late, it will deteriorate internally without external signs. Fruit size on unthinned trees is slightly larger than Bartlett. It has a good to very good rating for fresh fruit quality. When processed as pear halves, it has maintained its integrity, received good to very good ratings, and has been included in a CanAdapt pear trial. The tree is medium in size, conical and upright, annually productive and hardy. The tree has excellent resistance to natural fire blight infections (9.5 rating compared to Bartlett reading of 4.2), similar to Harrow Sweet and Harvest Queen. Following inoculation, lesion development may extend to about 15% of current season's growth. Precocity of AC™ Harrow Crisp is similar to Bartlett, trees coming into production about 4 years after planting. AC™Harrow Crisp is protected under the Plant Breeders Rights Act (application number 00-2184).

AC™ Harrow Gold (formerly HW 616) (Parentage: Harvest Queen x Harrow Delight)

Fruit are picked about 10 days before Bartlett, between Harrow Delight and Harvest Queen. An attractive yellow fruit, with good size (larger than Harvest Queen, similar in size to Bartlett), smooth skin, fine texture, very good flavour with a good balance between sweetness and acidity, and exceptionally juicy. The fresh fruit quality of AC™ Harrow Gold is rated similar to Bartlett. As with many other early season pears, the fruit will not store for very long (probably no more than 4-6 weeks) in common cold storage, but it is excellent for roadside stands. This cultivar has received good to very good processing ratings and has been included in the CanAdapt pear trial. AC™ Harrow Gold has excellent resistance to natural fire blight infections (9.6 rating); however, in some years following inoculation with the causative organism, lesions have developed which have extended to about 25% of current season's growth. Precocity in a second test planting appears to be similar to that of Bartlett. AC™ Harrow Gold is protected under the Plant Breeders Rights Act (application number 00-2185).

Harrow Delight

The fruit, smaller than Bartlett, are greenish yellow in colour with a red blush. The cultivar ripens 2 weeks before Bartlett and is resistant to fire blight. Pick fruit while still green; otherwise, it drops heavily. Harrow Delight is pollen-compatible with Bartlett, Bosc, Anjou and Harvest Queen.

Harvest Queen

The fruit resemble Bartlett in shape, colour, texture and flavour, but are smaller than Bartlett. Thinning will improve fruit size and reduce the tendency toward biennial bearing. Harvest Queen ripens 1 week before Bartlett and is as resistant to fire blight as Kieffer. Fruit hangs well on the tree and size will improve with delayed picking. Harvest Queen is pollen-compatible with Bosc, Anjou and Harrow Delight, but not Bartlett.

Harrow Sweet™ (PBR #0572)

Fruit size is comparable to Bartlett, colour is yellow with a red blush at maturity, and taste is sweet, juicy and excellent. The cultivar ripens 3½ weeks later than Bartlett and trees show good resistance to fire blight. Harrow Sweet is reciprocally pollen-compatible with Bartlett.

Kieffer

Strictly a canning pear of poor quality and a poor pollenizer for major pear cultivars grown in the province. Although it is highly fireblight resistant, most Kieffer plantings have been removed and planting Kieffer is not advised in Ontario.

Seckel

A very high-quality, attractive, productive, small, late pear. The core tends to break down in the middle near harvest. In Ontario it has been used for pickling. Seckel should be planted only in home gardens and for special markets in Ontario.

Pear Rootstock Descriptions and Recommendations

Pear rootstocks belong to several species of pear (Pyrus) and a few are even in different genera (Cydonia, quince; Crataegus, hawthorn; Sorbus, mountain ash). In the past, Bartlett pear seedlings (Pyrus communis) have been used exclusively in Ontario as the standard rootstock for pear orchards.

Pear rootstocks depends mainly on 3 factors:

• its adaptation to soil and climatic conditions
• its compatibility with commercial pear cultivars
• its susceptibility to certain diseases and insects.

Standard Rootstocks

Bartlett Seedling

At the present time most of the pear trees in North America are grown on seedlings of Bartlett. These seedlings produce vigorous trees and are adaptable to a wide range of soil and climatic conditions but they are all susceptible to fire blight in the nursery and orchard. Trees of Bartlett on Bartlett seedling rootstock are moderately vigorous and strong. The root system is composed of numerous, roots that are well distributed for anchorage. The fruit tend to be medium in size, fairly well shaped and high in soluble solids.

Bartlett seedling is still the main recommended rootstock for pear in Ontario.

Semi-dwarfing to semi-vigorous rootstocks

Old Home x Farmingdale Clones

The clonal selections OHxF 40, 69, 87 and 97 have been classified as semi-dwarfing in vigour compared to trees with standard rootstock and are under evaluation in a CanAdapt demonstration trial at various climatic locations in Ontario. Trees on these OHxF clones are productive and do not show excessive suckering. These clones propagate readily from hardwood cuttings and are all highly resistant to fire blight and winter injury. OHxF clones have been tested at the Mid-Columbia Agriculture Research and Extension Center in Hood River, Oregon.

Past trials at AAFC, Harrow with Harvest Queen indicate OHxF 69 and 87 are promising rootstocks while OHxF 333 produced a smaller tree but reduced fruit size.

The following OHxF clones are under test and have been included in the CanAdapt pear trial.

OHXF 40

Although it has only limited testing, early observations indicate that growth control with early production can be achieved.

OHXF 69

Trees from this rootstock may produce a tree approximately 70%-80% the size of a standard pear seedling. Reports from the west coast indicate that it may be somewhat susceptible to growing one-sided root systems.

OHXF 87

This rootstock is the highest producer of the Old Home series. It has demonstrated the ability to set fruit early and bear heavily. If allowed to crop heavy, it will give the grower a tree smaller than Bartlett Seedling.

OHXF 97

Is roughly the same size as Bartlett seedling trees but highly precocious. It is resistant to fire blight, pear decline, winter hardy and compatible with most cultivars.

Dwarfing rootstocks

In recent years, emphasis has been directed toward development of more precocious dwarfing rootstocks suitable for intensive pear plantings. For size controlling rootstocks, pruning and training systems need to be amended in order ensure the size controlling effect.

Pear growers have been limited to Quince selections (Cydonia oblonga) for use as dwarfing rootstocks. Table 3, 'Graft compatibility of pear cultivars on Quince rootstocks", lists the pear cultivars, which are compatible and incompatible, when grafted directly on Quince.

Table 3. Graft compatibility of pear cultivars on Quince rootstocks

Quince A

This rootstock is reasonably winter hardy (to -26° C.), tolerates excess soil moisture but not standing water, restricts vegetative growth of the pear scion cultivar, and induces fruit production at a younger age. It is not unusual to have fruit on 2 yr-old trees in the nursery or orchard.

Since the standard Bartlett is incompatible on Quince, Swiss Bartlett, a strain of Bartlett, which is compatible with Quince A, is used directly on Quince roots.

Bosc is also incompatible with Quince A. The cultivars Anjou, Duchess and Hardy are recommended for use as a graft compatible interstem. In research trials, Bosc with Old Home interstem has produced lower yields and smaller fruit. Trees of Bosc on Quince rootstocks are about the same size with all the interstems mentioned above.

Quince C

This is another clonal selection but has not proven to be as winter hardy as Quince A. It is more dwarfing than Quince A and very susceptible to leaf-spot fungus in the nursery. Quince C is presently under evaluation at Vineland.

Other Quinces

The major problem with Quince rootstocks is lack of winter hardiness in some regions of North America and Europe. Several clones with a reportedly higher degree of hardiness than Quince A have been developed and tested elsewhere.

Guidelines for planting and managing pear trees on Quince rootstocks:

1. Since Quince A is shallow-rooted, trees on this rootstock often lean severely after cropping begins. To reduce this problem, trees in the nursery should be high budded at 20 cm, leaving a long rootstock shank. At planting time set the trees so that only 2-3 cm of the rootstock shank are exposed above the soil line to prevent scion rooting. Each fall, remove accumulated soil and debris around the trunk area to expose the union. This approach will provide better anchorage and reduce the potential for rootstock suckering.
2. Provide trees on Quince A rootstock with a stake or trellis for additional tree support.
3. Fall planting of pear on Quince rootstock is not advised in Ontario. If pear trees on Quince rootstock are fall planted, carefully replace the soil to eliminate all air pockets around the root system and mulch the crown area of the trunks. Failure to carry out these procedures may result in significant winter injury to the crown and/or root system.
4. During the first 2 years in the orchard, protect the crown of the Quince rootstock with mulch in order to prevent cold injury to the roots. The mulch must be removed in spring. Good rodent control practices must also be followed to minimize risk of tree damage.
5. Do not crop for the first 3-4 years in the orchard. Remove the fruits as soon as possible in the spring. This allows proper formation of scaffold branches and establishment of adequate bearing surface area on the tree. Otherwise, the trees may become spur- bound, with reduced yield potential for the life of the orchard.
6. Since Bosc is not directly compatible on Quince A, use graft-compatible interstems (Anjou, Duchess or Hardy). Research findings at Vineland have shown that when interstems (Anjou or Hardy) are used for Bosc, yield and large fruit size are satisfactory.
7. Standard Bartlett is not directly compatible on Quince A. If Bartlett trees budded directly on Quince A are purchased, be sure that compatible Swiss Bartletthas been used.
8. According to experimental results obtained at Vineland, desirable spacing for dwarf pear plantings is 3.5 m. between rows and 2.5 m. in between trees (1143 trees/hectare or 453 trees/acre). Many factors, such as scion cultivar, soil and site, orchard equipment, orchard management and economics will influence the choice of tree spacing.

Pear Cultivars and Rootstocks

The following lists identify pears grown in the experimental orchards at the University of Guelph, Department of Plant Agriculture, Vineland.