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.
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.
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.
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.
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.
Popular in Hawaii. Produces very large, green and sometimes slightly yellow fruits with a pink flesh. Some fruits can weigh up to a pound.
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)
Medium sized, yellow skinned guava with spicy, cream-colored flesh. (Photo from www.specialtyproduce.com)
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.
Fruits are large and the flesh is thick and crispy when fresh. Fruit has a subtle color and flavor. (Photo from www.tradewindsfruit.com)
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.
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.
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.
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
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.
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.
Fruits are graded based on weight, size, and color. Fresh fruit has a short shelf life but can be extended up to 20 days when kept at low temperature of 5oC and 75-85% relative humidity. Good ventilation is necessary to reduce heat buildup. Guava is a delicate fruit requiring careful handling during harvesting and transportation. For long distance transportation, use of refrigerated transport and also proper packaging and cushioning material is required to enhance the shelf life of fruits.
Guava processing needs to be developed to lower the marketing costs and reduce losses in the production chain. Fruits can be dehydrated and powdered. Guava juice wine and guava pulp wine can be manufactured from ripe fruits. Good quality ready-to-serve beverage can be made from guava. The seeds contain 5-13% oil, rich in essential fatty acid and can be used in salad dressing.
In many countries, guava is eaten raw. Some consume it with a pinch of salt and pepper, cayenne powder or masala.
The fresh fruit is a very good source of vitamin C, pectin, calcium, and phosphorus. It can be processed to create products such as jams, jellies, and nectar.
Guava jelly has an attractive red-violet colour, pleasant taste, and sweet aroma. The puree can be used in juice, cakes, puddings, sauces, ice-cream, jam, and jelly. Fruits can be cut in halves or quarters and canned. Good quality salad can be prepared from ripe fruits.
In Mexico, the entire fruit is a key ingredient in punch. Pulque de Guava is a popular blend of the native alcoholic beverage.
Guava leaves are used in folk medicine as a remedy for diarrhea and diabetes. Tea made from young leaves is also believed to relieve dysentery and fever.
Research on guavas leaves have been done on their pharmacological properties. Most research, however, has been conducted on apple guava (P. guajava). Preliminary medical research in laboratory models, indicate that extracts from apple guava leaves or bark are possible treatments against cancer, bacterial infections, inflammation and pain.