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 Introduction / Agronomy |
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Guava (Psidium guajava) is valued for its delectable taste and aroma. Guava can be considered as the ‘apple of the tropics’ for its high vitamin C and mineral content. It is native to tropical America where it occurs wild. Early Spanish and Portuguese colonizers brought it to New World, the East Indies and Guam. It was soon adopted as a crop in Asia and in warm parts of Africa and is now widely grown all over the tropics and subtropics.
As a cheap nutritious fruit with a wide adaptability to diverse climatic and soil conditions, guava is an ideal crop to grow in developing countries.
Plant Description
The guava tree can easily be recognizable for its smooth, thin, brown bark that flakes off, exposing a greenish layer underneath. The tree can reach 33 ft (10 m) high, with a trunk of 10 in (25 cm) in diameter and spreading branches.
The leaves are evergreen, oval or oblong, has a short petiole, leathery, aromatic when crushed, and 2.75-6 in (7-15 cm) long and 1-2 in (3-5 cm) wide. The white flower is subtly fragrant, borne individually or in small clusters in the leaf axils, has 4 or 5 white petals, and a tuft of white stamens tipped with yellow anthers.
Fruit Description
The fruit ranges from round, ovoid, to pear-shaped, growing up to 2-5 in (5-12.5 cm) long. The thin skin varies in color from pale green to light-yellow, blushed with pink for certain cultivars. Underneath the skin is a layer of flavorful sweet and tangy flesh with color varying from white, yellowish, light pink, dark pink, or red. When immature, the fruit is green, hard, and very astringent. When ripe, some varieties have a custard-like consistency while others are crispy like an apple. The central pulp can be of the same color or darker than the surrounding flesh, is juicy and normally filled with very hard, yellowish seeds.
Common Varieties
Red Indian
Has a strong odor, medium to large size, round but slightly flattened at the base and apex, with medium thick, red flesh of sweet flavor, fairly productive in fall and early winter.
Ruby Supreme
Pungent, medium to large size, ovate, has thick flesh, sweet, relatively few seeds, excellent for eating fresh and for canning;,fairly productive, mainly in fall and early winter.
Beaumont
Popular in Hawaii. Produces very large, green and sometimes slightly yellow fruits with a pink flesh. Some fruits can weigh up to a pound.
Red Malaysian
Unique variety for its foliage and flowers, which are also tinted a deep red color. It is often grown for ornamental purposes as well as fruit. (Photo from www.freemalaysiatoday.com)
Mexican Cream
Medium sized, yellow skinned guava with spicy, cream-colored flesh. (Photo from www.specialtyproduce.com)
Safeda
Medium size, with very thin skin, thick, white flesh, few seeds and outstanding quality for canning. A famous guava, widely planted, but susceptible to wilt and branches are brittle and break readily.
Bangkok Apple
Fruits are large and the flesh is thick and crispy when fresh. Fruit has a subtle color and flavor. (Photo from www.tradewindsfruit.com)
Lucknow
Medium size, roundish, with creamy-white, soft flesh, sweet, pleasant flavor; very few seeds; good quality, bears heavily, keeps fairly well, not suitable for canning.
Propagation
The exact planting distance is specific to variety, soil fertility, and availability of irrigation facilities. As a rule of thumb, trees are usually planted at a distance of 5-8 m. Standard spacing is 6×6 m, accommodating 112 plants per acre. High density planting causes branches to grow upward, resulting to compact tall plants with higher yields in the early years of fruiting.
Seed propagation of guava is not encouraged because seedlings have a long juvenile phase, give lower yields, and bear poor quality fruits. Seedlings serve as rootstock for grafting or budding. The seeds should be sown immediately after extraction from the ripe fruits. Soaking of seeds in water for 12 hours or in hydrochloric acid for 3 minutes gives about 90% germination. About 1 year old seedlings become ready for grafting or budding.
Guava can be propagated by inarching but is cumbersome and gives limited number of plants from the mother plant. Budding can also be done with high success but can be labor intensive. Layering gives a high success rate but a limited number of plants can only be multiplied from a mother plant. Air layering of shoots is done during the rainy season but plants have a lower chance of survival.
Marcotting is the easiest and cheapest vegetative method of guava propagation. In marcots, sections of hardened shoots of a selected variety are scraped before a mix of moist earth, compost and rooting hormones are clumped at the spot before being wrapped with plastic material. If the marcots are successful, roots will appear in three weeks.
Guava can also be vegetatively propagated by cuttings, planted on sand beds.
Fertilization
Fertilizer doses vary from region and cultivar. Producers have been reported to use 600 N and 400 K; 260 N, 320 P, and 260 K; 900 N, 600 P, and 600 K; or 600 N, 300 P, and 300 K. Irrigation is provided at an interval of 20-25 days during the rainy season and 10-15 days during summer. Drip irrigation is recommended to save about 60% of water used for conventional irrigation.
Pruning
Training of plants at the young stage builds a strong framework and avoids weak crotches. Fruiting trees are pruned to prevent overcrowding. Plants are trained as low headed trees to help facilitate multiple hand pickings. Pruning also is important for increasing fruit size and yield.
Pest and Diseases
For more plant health information, including diagnostic resources, best-practice pest management advice and plant clinic data analysis for targeted crop protection, visit CABI’s Plantwise Knowledge Bank.
Pests mostly observed are fruit flies, stem borers, bark eating caterpillars, thrips, nematodes, mealy bugs, and scale insect. Chemical spraying with selective pesticides has been found to be effective. Certain cultural practices such as destruction of infected plants are recommended. Fruits are also bagged to prevent attacks from fruit flies.
Main diseases are wilt, fruit canker, fruit rot, anthrachose, and grey leaf spot. Application of Carbendazim/Thiophanate methyl or Kavach/Mancozeb has been found to be effective in controlling the diseases. Bronzed guavas result from low soil fertility and pH. Leaves of affected plants have purple or red specks. Under the worst conditions, defoliation can occur and fruits turn brown. Application diammonium phosphate and zinc sulphate at weekly intervals for two months reduces bronzing.
Fruit drop is a serious disorder in guava resulting in about 45-65% loss due to different physiological and environmental factors.
Harvesting
The plants start bearing fruits at 2-3 years, attaining full capacity at 8-10 years. The yield depends on age, cropping pattern, and the cultural practices. 10 year old plants yield about 100 to 150 kg every year. Guavas can be harvested throughout the year.
The best flavor and aroma of guava is achieved when it ripens on the tree. In most commercial varieties, fruit ripeness is indicated by yellowing of skin. For local markets, yellow but firm fruits are harvested, whereas light yellow fruits are picked for distant markets. Fruits are harvested selectively by hand along with the stalk and leaves.