Arlie A. Powell
Horticulturist-Fruits, Auburn University
ORIGIN & HISTORY
Asian pears originated in China and Japan and have been grown in these counties and certain other Asian nations for at least 3000 years. Records indicate Chinese immigrants introduced Asian pears to the west coast of the United States during the 1800's. The greatest concentration of present commercial production is in California and Oregon. The crisp and juicy texture and apple-like flavors of Asian pears have lead to many people referring to this fruit as the apple-pear. However, the Asian pear is not a cross between apple and pear.
Asian pears differ genetically from European (Pyrus communis) and the southern hard pears. They are primarily selections derived from Pyrus ussuriensis (Ussuri pear) and Pyrus pyrifolia (Japanese sand pear) or complex hybrids of the two species. European pears are grown to a very limited degree in Alabama because of high susceptibility to fire blight, a bacterial disease. The vast majority of European pear varieties, such as Bartlett, are not recommended for commercial or home use because of fire blight. Hard pears, also called sand pears, are grown quite extensively across the state and are much more tolerant of fire blight problems. Most varieties of hard pears such as Orient, Kieffer, and Garber, are generally considered crosses of European and Pyrus serotina, a Japanese pear. Flesh of these selections varies from extremely hard to very firm, with varying levels of grittiness. They are mainly used as processing fruits, although with proper storage some may be consumed fresh.
TYPES & VARIETIES
Asian pears may be divided into the Japanese varieties which have round fruits and somewhat similar to an apple in size and shape and Chinese varieties which produce fruit more pear-shaped (pyriform) like European varieties. Most of the varieties showing promise in Alabama are of Japanese origin. Japanese varieties may further be divided on the basis of their fruit skin texture, which is smooth or russetted. Smooth skinned varieties range in skin color from green to greenish yellow, while russet skin type varieties range from brownish green to brown or copper colored. Another difference between Asian and European pears is that fruit of European selections are harvested and ripened off the tree in storage, while Asian pears are allowed to ripen on the tree before harvesting. A ripe European pear has soft, melting texture, and creamy flesh while Asian pear fruits are very firm, crisp, juicy and very sweet (low acid).
Variety evaluation of Asian pears has been conducted by Caula Beyl, Alabama A&M University, and William Dozier and Arnold Caylor, Auburn University. Applied research as well as grower variety demonstration studies have been conducted by Arlie Powell and Ed Tunnell, Auburn University. Most of these evaluations have been made during the last five to ten years. During this period, a number of commercial fruit producers have also made their personal evaluations of a number of varieties established in orchards.
The varieties that have been under evaluation for the past several years at one or more locations include: Chojuro, Daisu Li (12- 44UC), Doitsu, Erishinge, Housi, Ishiwase, Kikusui, Kumoi, Megeitsu, Niitaka, Okusankichi, Seigyoku, Seuri, Shinko, Shin Li (12-43UC), Shinseiki, 20th Century (Nijiseiki) and Ya Li (Table 1). Shin Li and Daisu Li are selections from California. Ya Li is the only Chinese type Asian pear in these studies. Evaluations to date are fairly clear on several matters involving varieties but still haven't provided all the answers needed for making solid recommendations for commercial production.
Seuri and Ya Li flower too early for consistent production in northern and central counties because of damage from freezes. Thus far, Housi and Shinko are the main two varieties recommended for commercial and home use. Both varieties produce large, attractive and flavorful fruit with 12 to 14% soluble solids. Housi is considered by many to have the best flavor of all varieties tested thus far. Other varieties which may prove suitable for commercial and/or home plantings include Shinseiki, Doitsu, Megeitsu and Chojuro. Grower evaluations of two other varieties, Early Asian and Korean Giant (A-Ri-Rang) are promising. Early Asian is the earliest in ripening of Asian pears available and has good flavor. Its origin is unknown. Korean Giant appears outstanding with extremely large fruit and 14.5% soluble solids. It ripens very late, after other selections are well past harvest, and has excellent flavor.
Four different rootstocks for Asian pear have been evaluated at Alabama A&M University. They include European pear (Pyrus communis) and three Asian pears (Pyrus betulaefolia, Pyrus calleryana and Pyrus ussuriensis). Because of imparting greater fire blight resistance to varieties budded onto it plus other desirable characteristics, Pyrus calleryana is preferred rootstock for Asian pears grown in the Southeast. This is the same rootstock used for hard pears and European selections grown in the Southeast.
In general, Asian pears may be grown using the same type cultural program for European pears. Trees are quite winter hardy and have somewhat lower chilling requirements than most European varieties. However, additional work is needed to determine more closely the chilling requirements of varieties at temperatures of 45F and lower. It appears many varieties have chilling requirements in the 750 to 850 hour range with some lower. For example, Housi can grow and fruit reasonably well with 550 to 650 chill hours while Shinko requires at least 800 or greater for best performance.
Asian pear varieties vary in their susceptibility to fire blight, but observations to date indicate most are as susceptible as apples such as Golden Delicious, but somewhat less susceptible than European pears. It is necessary to use fire blight sprays (such as streptomycin) annually during bloom, whether grown for commercial use or in home plantings. Don't plant Asian pears unless fire blight sprays are used. Most growers to date have used minimal additional sprays for insect, mite and disease control, and only time will tell how much more intensive cover sprays will have to become to handle problems as they develop.
Asian pear trees easily begin bearing in the 3rd and 4th growing seasons and are producing several bushels per tree by the 6th growing season. Most varieties need to be spaced a minimum of 10 to 15 feet in the row with rows spaced 16 to 20 feet apart.
The training/pruning program is similar to that for European pears. Although they can be trellised, because of their vigor and ultimate size on P. calleryana rootstock, it is best to manage Asian pears as free-standing trees. Because of fire blight problems, a modified leader, multiple scaffold (4 to 6 branches) tree form is probably more sensible than using single trunk, central leader training, although both will work. Some training of scaffold branches, much like practiced with apples, is desirable in attaining ideal tree form.
Fertilization is suggested during the first two or three years to develop the desired tree structure. However, once trees begin fruiting only very moderate amounts of fertilizer should be used. This may involve from none to 10 to 30 lbs. of nitrogen per acre per year depending upon tree vigor, cropping and previous history. Fruit thinning may be needed in some years. Because ideal chemical thinning hasn't been developed, it is usually best to thin fruits to one per cluster or one every 4 to 6 inches when 3/4 to 1 inch in diameter and after the freeze period has past.
Many Asian pear varieties are considered partially self-fruitful (can produce up to a 15% crop from self-pollination) but it is best to always plant at least two varieties to ensure cross-pollination and full cropping potential. It should be noted that Ya Li is the earliest variety to bloom followed closely by Seuri and Niitaka. To date, Seuri has been able to pollinate Ya Li resulting in at least moderate crops. The latest flowering variety is Okusankichi with Kumori next latest. Housi, 20th Century and apparently a number of the other varieties are self-incompatible and will always need pollinators. Niitaka has sterile pollen and can't be used as a pollinator. Shinseiki is a good pollinator for a number of varieties (except Seigyoku) and has been reasonably self-fruitful. It blooms mid season. Note that some varieties are not cross- fruitful with other varieties such as the Shinseiki/Seigyoku combination just noted. Housi and Shinko are good pollinators and work well together. Flowering time for most Asian pears is slightly after peaches and before apples but it varies from year to year.
HARVESTING & MARKETING
The ripening period for Asian pears begins in mid July in southern counties and can last through early to mid September in northern counties. Fruits are harvested as they become ripe on the tree (ready for immediate consumption). Fruits may easily be stored in conventional refrigeration at 32 to 35F for one to three months (longer for some varieties). However, most fruits are sold fresh and stored for only short periods in the state. One of the harvest season problems growers have experienced is that winds and rain easily dislodge fruits from trees when ripe, creating possible crop loss.
Marketing the limited supplies of Asian pears now being produced in the state through roadside retail farm markets has only been partially successful and reflects the somewhat slow acceptance of this fruit by consumers in the Southeast. One of the problems confronting this fruit is that it ripens when some of the finest flavored peaches are available, and the peach is usually favored by most of the public. However, Asian Americans in general are strong purchasers of Asian pears. Hopefully the Asian pear will eventually prove very compatible with the peaches and early apples being marketed during the same time frame and afford the consumer greater variety. In spite of the commercial problems, the Asian pear clearly affords the home producer with a fine alternative crop.
Asian pear now appears to be an alternative fruit that can be grown successfully across most of Alabama. Some problem areas still remain to be solved before a completely satisfactory cultural program can be developed, but the potential for the crop is promising. Among the major obstacles to successful production of Asian pears are: developing cultural programs to minimize fire blight and crop loss from late freezes; developing ideal variety combinations for each area of the state (cropping can be poor in extreme south Alabama in low chilling years); development of strategy to lessen problem of premature fruit droppage; and lastly, enhancing the marketing acceptance of this fruit.
Table 1. Characteristics of Asian Pear Varieties1.
|VARIETY||TYPE SKIN||HARVEST SEASON2||FRUIT SIZE|
|Early Asian||smooth, greenish yellow||very early||medium|
|Shinseiki||smooth, greenish yellow||early/mid||medium-large|
|Seuri||mostly smooth, green||mid||small-medium|
|Shinko||some russet, brownish green||mid||large|
|Ya Li||smooth, green||mid||small-medium|
|20th Century||smooth, green||mid||small|
|Megeitsu||some russet, brownish green||mid/late||medium|
|Korean Giant||some russet, greenish yellow||late||very large|