PEARS (Pyrus Spp)
Pears are a fruit trees native to coastal and mildly temperate regions that belong to the Pyrus family. The trees are medium sized, about 10–17m tall, often with a tall, narrow crown. Pears have a distinctive bell shape fruit. Some pears have knobby lobes at the base of the fruit while others are smooth at the base. The skin of the fruit ranges in colour from green, yellow, red, brown, pink, or a combination of these colors. Pear flesh is white, juicy and grainy in texture.
Pear cultivars can be divided into 3 main groups originating from 3 species:
- Pyrus serotina
Hybrids of apple are increasingly important as indicated their wide distribution.
Asian pears are divided into the Japanese cultivars which have more-or-less round fruits, and Chinese cultivars which produce more pear-shaped fruit. Japanese cultivars may further be divided on the basis of fruit skin texture; smooth or russet.
The descriptions given here cover Asian pears and their hybrids, which appear to be better adapted to the Kenya highlands than European pears.
- Asian pears generally have an upright growth habit and may grow to 10 m tall. Shoots grow in flushes, the number of leaves being limited in spurs.
- The annual cycle of growth is similar to that described for apple. Flowering takes place before or together with unfolding of leaves.
- Self-incompatibility is common but parthenocarpic (i.e. seedless) fruit set occurs.
- Fruit mature in 4 to 5 months.
|The tree growth is medium to vigorous.
It is upright, sparsely branched with long internodes.
Has broad, round–oval leaf with attenuated tip and medium coarse serrations. Chilling requirements are medium at about 400 hours. The cultivar needs pollinators.
Fruit is early-maturing (115–125 days after full bloom), russet brown and flat to globular in shape and of reasonable size (about 130 g). Lenticels are conspicuous. The fruit flesh is cream in colour. The juicy, very sweet, crisp and slightly gritty. The cultivar is of medium production but good storability.
|The tree is vigorous when young but more moderate when mature. It has a weeping habit with long, floppy limbs. The leaves are broad ovate to oval with attenuated tip and medium serrations. Chilling requirements is moderate ( about 450 hours).
The russet golden brown skin shows plenty of prominent white lenticels.
Due to its high sugar-to-acid ratio and fine grained texture this is one of the tastiest Asian pears. Production is medium to high and fruit stores well for 4 to 6 weeks.
It has dessert quality.
|Tree has low to moderate vigor, very upright and extremely productive. Despite being a heavy yielder, it is an annual bearer. It has oval leaves with attenuated tip and small, neat serrations. It has moderate chilling requirements (about 450 hours).
Fruits are large, more round than conical and slightly flattened with a beautiful bronze-russet thick skin. It is a late ripening cultivar of excellent quality and ripens in about 150 to 170 days after full bloom. The fruits are juicy, sweet, refreshing, and crisp. Shinko is a useful pollinator and is partially self fertile. Fruit stores well for up to 4–5 months.
|Tree is vigorous in growth, very productive, but susceptible to fire blight. Leaves are roundish with attenuated tips and medium serrations.
Chilling requirements are medium. It is partly self-fertile, but more productive if inter-planted with Hosui. A very late maturing cultivar, picking may start 195 to 210 days after full bloom.
The fruit is big, turbinate or globular and slightly irregular in shape. The fruit is russet brown, dull greenish brown to tan brown. At harvest the fruit has only a fair flavour and moderate quality which improves (sugar–acid content) with storage.
(Pyrus communis x P. serotina)
|Tree is the easiest cultivar to grow. It is very vigorous, upright and fruitful.
Chilling requirements are low and heat endurance is excellent.
Yields are medium to high, and no pollinator is needed. The tree is well adapted to a wide geographical range and to a great diversity of soils and climatic conditions.
The fruit is of medium to large size, oval and narrowing at both ends, with a thick stalk. Flesh is firm, yellowish-white, moderately juicy, tasty but sometimes very granular. The skin is thick, tough, and smooth with large lenticels. It is green-yellow, blushed with dull red on the exposed cheek. Storability is very good and the fruit never becomes soft. Although the dessert quality is low, the canned product is usually good.
|Shinseiki (New Century)
|The tree is vigorous, upright, heavy bearer (often starting in its second year), and easy to grow. It is a self pollinator, with moderate chilling requirements (about 350 to 450 hours).
The fruit is egg-shaped, bright-yellow skinned, firm and medium-sized. The fruit has medium to large brown lenticels with freckling peel.
Fruits hold on the tree well and are often handpicked 2–3 times per season. Heavy thinning is necessary for good fruit size.
Fruits have a thin skin and a firm, juicy, sweet, and crisp flesh. They mature early and store well for up to 3 months.
|Tree is very vigorous, upright, and dense, with low chilling requirement (about 300–350 hours). Leaves are large, oval, with attenuated tip and have very fine, neat serrations. It is a late cultivar which will ripen in 150–190 days after full bloom. It is partly self-fertile.
Fruit is medium to large (140–310 g), 5–7.5 cm in diameter, pear shaped, light green to yellow and may have unattractive lenticels spotting. It has good eating quality, high sugar content, sweet, crisp with a trace of tartness. It has a fairly long storage life of 6–7 months in at 0–1 ºC.
|The tree has medium to strong vigour and an upright growth habit. Chilling requirements are medium to low, and productivity is high.
Fruit is large (150–200 g), irregularly shaped and short necked with greenish skin, turning yellow when ripe. The flesh is finely textured, creamy white, sweet and juicy. It is an excellent dessert pear, with very good cold storability of up to
4 to 5 months.
|The tree has strong, upright growth and low chilling requirements. It is of medium production.
It requires a pollinator (Kieffer variety). It is inclined to produce small fruit, so thinning is advisable.
The fruit is an attractive green-yellow, red-blushed pear. It is medium-sized, oblong, and pyriform shaped with conspicuous lenticels.
It tastes has a sweet but texture is slightly coarse. Has very good storability
|The tree is moderate in vigour,upright in growth and forms a spine-like shape.
A very heavily cropping cultivar but only of fair quality. It is self sterile.
Fruit are small-sized and round to conical. Skin is rough, dull yellow and almost covered with brown russet.
Fruit appearance shows open eyes set on the surface of fruit. Flesh is yellowish, very juicy, crisp, half-melting or crackling, but has poor or little flavour. It has very short storability.
|The tree is of moderate vigour, a good cropper, and has adapted well to Kenyan highland climatic conditions.
Fruit is oblong–ovate to pyriform (tapering towards the stem end and rounded at the apex).
The skin colour is mainly green-yellowish, but with a reddish blush if exposed to the sun.
It is waxy skin with conspicuous lenticels. Flesh colour is white, texture fairly melting, and the taste juicy and sweet. Has short to medium storability.
|Tree is moderately vigorous with a rather straggling growth habit.
It is a heavy cropper and a tip bearer.
Fruit is medium sized, long and conical. The fruit is of good quality, but should be picked and used as soon as ready because it is prone to rotting from the core. The skin is fairly smooth, greenish-yellow, with some brownish-red flush and russet patches on the sun-exposed side. Flesh is pale yellow, tender, juicy and sweet.
Suitable Cultivars for different zones
||These varieties have low chilling requirements: Baldwin, Beurea BOSC, Coscia, Douglas, Garber, Hood, Keffer, Le Conte, Packman Triump, Pinneapple, Richard peters, Smith Hybrid and Wilder Early
||These varieties have high chilling requirements:Compat, Doyenne du Comice, Fertility, Hardy, Jargonelle, Spadona, Will, Williams Bon Chretien and Winter Nelis
Depending on their chilling requirement, pears do very well at elevations of approximately 1,700–3,000 m asl (which include areas such as Limuru, Tigoni, Kikuyu and Molo in Central Kenya). Generally, Asian pears and their hybrids can be grown at considerably lower elevations than European pears in tropical regions.
Pear trees are reasonably tolerant to drought and excess soil moisture during the rest season.
The pear thrives on a variety of soils but it does best in fairly rich, well drained loam soils of moderate depth, underlying a porous subsoil with sufficient organic matter. They can tolerate slightly acidic soils, with an optimum pH of about 6.0–7.0.
A cold season is required to break bud dormancy. Lack of chilling leads to delayed foliation and poor, uneven fruit set. Cultivars differ greatly in their chilling requirements, and in some cases up to 1000 hours below 7 °C are needed. For Kenya, pears with low chilling requirements are necessary. Accordingly, appropriate varieties are: Flordahome, Hood, Tenn, Spadona, Gentil, Shinko, Kosui, Nashpati, Tsuli, New Century, 20th Century, Taiwan Hybrid, and Senseke, among others. Of the Chinese cultivars, Tsuli and Yali show the most promise for East Africa.
Propagation of Pears
Pear cultivars are not true to type when grown from seed. Therefore, vegetative propagation has to be used. The most common method of pear cultivar propagation is grafting and budding.
The pear trees of some cultivars, e.g. Keiffer can be successfully propagated vegetatively by hard wood cuttings. In this case no budding is required.
The pear is similar to the apple in its cultivation requirements but wider planting distances should be applied depending on the cultivar and location.
- A Spacing of 3–4 m within the row and 4–6 m between the rows should be sufficient.
- Most pear cultivars are self-infertile (Asian pear cultivars are only partly self-fertile), and cross-pollination is generally required to ensure a commercial crop.
In Kenya rootstock for pears are usually propagated vegetatively through stooling. Malling Quince A is a more vigourous rootstock while Malling Quince C is moderately dwarfing in effect and brings the tree into cropping slightly earlier. The latter is not good for under poor growing conditions.
Certain varieties are incompatible with quince and will need an intermediate stock in order to graft them.
The land should be cleared of vegetation and if possible ploughing should be done. Planting holes of 60 x 60 x 60 cm deep should be prepared well in advance, 2-3 months earlier. The top soil should be placed aside, mixed with manure and returned to the hole. The sub soil can be used to form the rim or catchment of the basin. The soil in the hole should be allowed to settle before planting is done
Planting is done like the other trees. Some pear varieties are self sterile and will need other varieties for cross pollination. These should not be more than 3 m away.
3 x 2 m (dwarf trees or with regular pruning)
4 x 3 m (large trees or with standard pruning)
Just before planting, 110-170g/m2 of, NPK, 20:20:0 or 23:23:0 should be mixed with the soil. Fertilizer is not generally needed as much as in other fruits, but some nitrogen and phosphorus may be useful. Too much nitrogen however encourages nitrous growth and gives greater susceptibility to fire blights. Every rainy season a general fertilizer such as NPK may be applied at the rate of 110-225g/m2 depending on the growth of the tree. An annual mulch of decayed manure will also help to keep the trees in good condition and will cater for their nitrogen requirement which is higher than for apples.
The most effective fertilizer programme can be reached based on leaf and soil analysis
It is possible to grow other crops in a pear orchard.
Pruning is needed to keep the trees low enough for harvesting and to improve production. Light to moderate pruning gives best yields.
General pruning for established bush trees involves cutting the laterals back to three or four buds and reducing the fruit bud on the spurs to three or four in number. At the same time the leaders may be shortened by half their length.
Most pear varieties are spur bearing, but in case a variety is tip bearing, then be careful not to cut back too many of the fruit bearing laterals.
Removing excess fruit ensures satisfactory development of colour, shape, and size of the remaining fruits. Over-cropped trees are also prone to serious limb breakage.
Leave one pear per cluster and space these about 10–15 cm apart. If fruit set on a tree is not excessive, 2–3 fruits per cluster will reach satisfactory size without thinning. The earlier thinning is completed, the more effective it is at achieving the desired results.
Pest and Diseases
Whereas the common Asian pear suffers little from diseases and pests, improved cultivars, and European pears, require fairly intensive crop protection.
|Scab (Venturia spp.)
||Scab first appears as velvety, dark olive-to-black spots on fruit, leaves, and stems. When infections occur early, fruit spots become scab like with age and the fruit may become misshapen.
On leaves, infections cause leaf puckering and twisting and eventually the leaves tear with age. Secondary infections that occur later in the season appear as black, velvety pinpoint spots on fruit and leaves.
Pear cultivars differ in their susceptibility to scab.
|Use Recommended fungicide e.g. Antracol, milthane super
Plant less susceptible varieties.
|This is one of the most serious and economically damaging diseases of pears. Infection is triggered by heat and moisture, and can spread rapidly even within a matter of hours.
It can be transmitted by bees, aphids, psylla, or other insects, and can also be spread by wind and rain.
Pruning can be another source of infection.
Affected branches wither and turn black or brownish black, as if scorched. Most branch tips, once infected, wilt rapidly, taking on the characteristic shape of a “shepherd’s crook.” The bacteria gain entry to the tree through blossoms or lush new growth and, once inside, begin to work toward the roots.
If the disease spreads unchecked to the trunk and roots, it can kill the tree; however, in resistant varieties the bacteria rarely invade beyond young wood.
Minimum fertilization applied.
Choosing resistant pear cultivars e.g. Keiffer
Use Recommended fungicide e.g Nimrod 25EC, Ridomil Gold MZ 68WG, Topsin M at green-tip stage that provides some protection from infection.
|Root rots (Armillaria spp.)
||It is spread on infected woody material by farm machinery or flood water. Affected trees usually show a general decline in vigor over years.
The key symptoms include patches on trees which get larger each year.
To confirm the presence of Armillaria, dig around the crown of the tree and scrap off the bark on small sections of the crown and main roots. It is easy to see the dense, felty, creamy white-colored plaques of mycelium between the bark and the wood. Infected wood will have a strong mushroom smell and feel slightly spongy.
|Avoid planting in recently cleared land with residual tree roots
|Powdery mildew (Phyllactinia spp.)
||The fungus produces a white powdery growth on new terminal growth and developing fruit.
The fruit infection appears as black marks and russeting on young fruit.
|Avoid overcrowding of trees and branches.
Prune out twigs with white fungus growth on the surface. Use Recommended fungicide e.g. Antracol, Milthane super, Topsin M
|They sack sap on plant tissues. This causes distorted or stunted growth. The excess sugars are excreted as honeydew resulting to formation of mould on the tree. The presence of honeydew makes the fruit sticky and a black fungus grow in it, giving the fruit a sooty appearance.
||Predators and parasites often reduce aphid populations. These include: Lady bird beetles (Hippodamia convergens, Coccinella spp), green lacewing larvae (Chrysoperla carnea)
Use selective insecticides to avoid killing natural enemies
|Red spider mites (Paninychus ulmi)
||Stippled and bronzed leaves that may turn brown and dry. They also cause russeting on fruit.
||Use of recommended insecticides e.g. Ortus 5SC, Omite, Mitac 20EC, Kelthane 18.5EC
|Thrips (Frankliniella spp)
||They have sharp, sucking mouthparts, which destroy plant cells. The females begin by laying eggs in the petioles and midrib of leaves and on the fruit.
Leaves appear mottled yellow to green-brown, dwarfed and cupped with brown margins. Severe defoliation can occur with heavy infestation.
|Use of recommended insecticides in severe infestations e.g. Atom 2.5EC, Decis, Evisect S, Karate, Achook EC
|False codling moth
||Larvae penetrate the fruit skin, bore into the core, and feed in the seed cavity. Larvae may enter through the sides, stem end, or the flower. One or more holes plugged with frass on the fruit’s surface are a characteristic sign of codling moth infestation. Flower entries are difficult to detect without cutting the fruit.
Removal of all infested fruits.
Thrips Damaged leaves showing leaf burn caused by
red spider mite
Damage by codling moth Mature codling moth larva
Powdery mildew on pear fruit Pear scab
Harvesting of pears
Pear yields vary according to the age of a tree, the cultivar, crop husbandry and location. A healthy young tree is expected to produce 2–7kg of fruit, a five-year-old tree 13–23 kg and a mature tree 45–180kg
Pears take longer than apples to begin fruiting, usually 3 to 5 years after planting. All pear fruits, whether intended for the market or for use at home, should be hand-picked with care.
Indications of picking maturity
- Pears are ripe when flesh around skin gives in to gentle pressure.
- When there is a perceptible change in the skin colour.
- When the seeds begin to turn brown.
- When the stalk separates readily from the branch when the fruit is lifted lightly.
These tests are an indication of picking maturity only; most pears will need to be store-ripened before they are ready to eat.
- Early varieties of pears should be used as soon as possible after picking since they do not store well. Late varieties may however be stored in a cool dry place.
- European pears may be harvested for ripening off the tree in storage, while Asian pears are allowed to ripen on the tree before being picked.
A ripe European pear has a soft, melting texture and creamy, aromatic flesh, while Asian pear fruits are very firm, crisp, juicy and very sweet
Post harvest handling
If not consumed immediately, well treated and packed fruit can be stored for several months at a constant temperature of –1° to 2ºC and relative humidity of 85–90 %. Maximum storage life in pears is cultivar-dependent.
Pears may be stored at room temperature until ripe. Fruits are optimally stored refrigerated, uncovered in a single layer, where they have a shelf life of 2 to 3 days.
Pears are an excellent source of dietary fiber and a good source of Vitamin C.
The fruits are consumed fresh, canned, as juice or dried. The juice can also be used in jellies and jams, usually in combination with other fruits or berries.
The fruits are generally sold in the local market.