GUAVA (PSIDIUM GUYUVA)
Guavas originated from South America. They are plants in the family (Myrtaceae) genus (Psidium). It is a large dicotyledonous shrub, or small evergreen tree, generally 3-10 m high. The trees are cultivated for their edible fruit. It is both cultivated and grows wild. The branches are very strong and highly tolerant to high winds.
Guava fruits are round or oval depending on the species. The outer skin may be rough, often with a bitter taste, or soft and sweet. The fruit is usually green before maturity, but becomes yellow, maroon, or green when ripe depending on the variety. The fruit flavour may be sweet or highly acidic. The fruits are rich in vitamins A and C. The seeds are rich in omega-3, omega-6 polyunsaturated fatty acids and especially dietary fiber.
The following superior cultivars have been introduced into the country:
Cultivars with high sugar content;
- Hong Kong Pink: Medium to large, roundish fruit, flesh is pinkish-red, very thick and smooth-textured with sub acid to sweet flavor and few seeds. The tree has a spreading growth habit and high yielding
- Malherbe: Fruits used for canning
- Fan Retief: The flesh of the cultivar is orange pink with a granular structure as a result of the many stone cells. There are numerous hard seeds embedded in the pulp.
Cultivars with high acidic content;
- Beaumont: Tree is vigorous, wide spreading and very productive. The fruits are medium to large and round with pink, mildly acidic and seedy flesh. It is excellent for processing. It is very susceptible to fruit rots.
- Detwiler: Tree is a very heavy bearer. The fruits are round, medium to large with greenish-yellow and moderately thick skin. The flesh is yellowish to light pink in colors, medium firm, relatively sweet and of pleasant flavor.
- Ka Hua Kula: The tree is a heavy bearer. The fruit is large, with thick, deep-pink flesh, and fewer seeds than ‘Beaumont’ and is less acidic.
They do well at altitudes 0- 2000m asl.
For maximum production, guava requires 1000-2000mm of well distributed rainfall throughout the year. Guavas can also grow in areas with rainfall of 900mm. If ripening occurs during wet period the fruits lose flavor and may split. The tree tolerates both marked dry spells and water logging.
Guavas are best adapted to the warm climate. The trees can thrive in both humid and dry climates, but can survive only a few degrees of frost. Young trees are particularly sensitive to cold spells. Optimum vegetative growth occurs between 15 and 28 °C while mean temperatures of 23 to 28 ° C gives the best fruit yield. Temperatures higher than 32 °C and below 3 °C are regarded as restrictive for cultivation of guavas.
The guava tree can grow in a wide range of soil types, from sandy to heavy loam. It can also grow in poor soils (shallow, gravelly and rocky soils) with reasonably good drainage; however growth and production are better on rich clay loams with high organic matter.
The optimum pH range is 5 – 7. The tree does not tolerate salty soils.
- Plough and harrow well before planting.
- Dig holes 60 x 60 x 60 cm. Spacing depends on topography, land use Separate top soil and sub-soil and loosen the base of sub soil on reaching the required depth.
- Refill the hole 1 month before planting using top soil mixed with fully decomposed manure at the rate of 20kg per hole.
Guava plants are commonly propagated from seeds: however, vegetative propagation techniques such as air layering, grafting and budding are highly encouraged.
1) Vegetative propagation
Propagation of guavas is mainly done through air layering a method of propagating new trees from stems still attached to the parent tree. The stem is wrapped with damp moss to encourage root formation
2) Seed Planting
Guavas grown for processing may be propagated by seed; about 70% of seedlings retain the general characteristics of the parent tree. One fruit will supply over 50 seeds, which should produce at least 25 good quality seedlings.
Select seeds from healthy, outstanding mother plants of a known variety. The fruits should be fresh and ripe. The seeds are easier to remove when fruits are allowed to ferment for a few days in a container filled with water. The seeds are washed in fresh water to remove all the flesh. Seeds can be either dried or planted immediately.
The seeds are then sown in a seedbed, containers or directly to the field. If planted directly, 3 to 4 seeds should be sown per hole at a depth of 1 cm.
Germination occurs within 15-20 days. The seedlings should be transplanted when about 25 cm high. The seedling grows very rapidly, producing fruit in 2-3 years on good soils.
The seeds germinate in 1 to 4 weeks and are ready for grafting in 3 to 4 months, when they reach a thickness of 1 cm.
Cleft grafting is the method most commonly used. Avoid grafting during the wet season. Plants are ready for transplanting 2 to 3 months after they have been grafted.
Spacing in the field
Under high management space the plants at 4 x 5 m
Under low management space the plants at f 5 x 6 m or 6 x 7 m
When planting grafted seedlings, position the graft union 30 cm above the ground. Plant the seedling at the same depth as it was in the nursery. Fill the planting hole completely with soil after transplanting.
The young trees should be trained to single stems. After the stem reaches a height of 60cm, prune to leave only 5 well spaced side branches. Prune every season after harvest to enhance flowering and vegetative growth. All dry wood and branches should be removed.
When the trees are young the orchard should be kept weed free. Large trees tend to have no weeds under them.
Fertilizer and Manure
Apply fertilizer at the rate of 1.5 to 2.0 kg CAN and 1.5 kg super phosphate for a fully grown tree. Apply farmyard manure at the rate of 40kg per year before the rains and incorporate it well into the soil.
|Pest||Description and Damage||Control|
|Fruits Flies (Daucus dorsalis Hendel)||These are the most serious pests of guava. The flies are 4-7 mm long, brightly coloured, usually brown-yellow-black patterns; wings are spotted or banded with yellow and brown margins.Eggs are laid into the maturing fruit, where they hatch into small maggots.
The maggots are creamy-white, up to 6 mm long.
The maggots burrow through the pulp, making them unsuitable for human consumption
Maggots emerge from the fruit to pupate in the soil.
|Orchard sanitation, destroy rotten fruits, pruning off the trees, Sprays with suitable insecticide e.g. Decis 2.5EC, Karate 2.5WG, Achook|
|Mealy bugs (Planococcus lilacinus)||These are small (about 3 mm long), elongated-oval insects with pale pink coloured, soft bodies mostly covered with a waxy secretionThey secrete honey dew, a sticky substance on which a black fungus (sooty mould) grows discolouring the fruit.
Ants are attracted by the honeydew, which hampers the activities of the natural enemies such as ladybird beetles and parasitic wasps.
|Natural enemies such as space the plants at parasitic wasps and predatory beetles usually control mealy bugs.Avoid unnecessary use of chemicals that kill natural enemies.|
|Green scales(Coccus viridis)||These are soft and armoured scales often found in low numbers on guava trees.||Natural enemies ladybird can effectively control scalesAvoid unnecessary use of chemicals that kill natural enemies.|
|False codling moth (Crypophlebia leucotreta)||The eggs are deposited on leaves and the fruits. Hatching caterpillars are white and later turn pink, penetrate into the pulp causing a yellow patch on fruit skin around the entry point.||All infested fruits both fallen and on trees, should be destroyed by burying not less than 50cm deep.Use recommended insecticides e.g. karate, Dynamec 1.8 EC, Bulldock Star|
|Coconut bug(pseudotheraptus wayi )||The bug is a major pest of coconut but also attacks other fruits trees such as avocado and guava. They are found in the coastal areas of Kenya and Tanzania.||Natural predators such as ants feed on the bugs.Use selective insecticides to avoid killing natural enemies e.g. Pesthrin.|
|Spotting of leaves and fruits(Cepaleuros mycoides Darst)||Spotting of leaves and fruits caused by the parasitic alga. It is rather severe on some cultivars in humid areas.||Use recommended fungicide e.g. Amistar 250SC, copper based fungicides|
|Anthracnose or Canker (Gloeasprrium psidii)||Formation of circular, dry and raised cankerous spots throughout the fruit surface. Infected fruits become undersized misshaped, hard and dry. It also causes dieback of plants. On the leaves, the disease produces angular, rusty brown spots of varying sizes, usually 2-5 mm in diameter||Maintain clean field through removal and destruction of diseased fruits and twigs.|
|Wilting(Gloremella psidii Sheld)||The disease causes mummification and blackening of immature fruits.||Field sanitation.Use of clean planting materials.|
- Trees that are raised from seed start bearing fruit after 2 years and continue fruiting up to 30 years.
- Budded or grafted trees may bear as early as the first year. However economic yields are obtained in the 6th year.
- Normally the best picking time is when the fruit starts to turn yellow, but this differs with cultivars. Immature fruits do not ripen off the tree. They may be soft but do not develop flavor or colour.
- The harvest interval should not exceed 4 days to avoid loss of overripe fruits.
- Mechanical damage increases the extent to which the fruit can be infected by fungi. Harvesting practices should, therefore, be directed to keep mechanical damage to an absolute minimum.
- Use shallow containers when harvesting and transporting the fruits to avoid crushing them. Keep harvested fruits in the shade.
Annual harvests of 25-40 tons/ha can be achieved.
The guava tree has a life span of about 40 years, and it may bear heavily for 15-25 years.
- Guava fruit has high respiration rate hence refrigeration is a very important aspect. The period between harvesting and refrigeration should, however, be kept as short as possible. The suitable storage temperature is approximately 5 °C.
- Harvesting should be done during the cooler part of the day and the fruits should not be exposed to the sun.
- The fruit should be packed in a single layer to avoid damage during transportation.
The ripe fruit is usually eaten fresh. It can also be utilized in many ways to make jellies, jam, paste, juice, baby foods, puree, beverage base, syrup, wine and other processed products. It may be eaten sliced with cream and sugar and as ingredient in cakes and pies.
Guava fruits are destined for domestic and export markets.