Description
Papaya,
Carica papaya, is an herbaceous perennial in the family Caricaceae grown for its edible fruit. The papaya plant is tree-like,usually unbranched and has hollow stems and petioles. The leaves are palmately lobed, spirally arranged and clustered at the growing tip of the trunk. Papaya trees can be male, female or hermaphrodite and the type of inflorescence produced is reflective of this. Male trees produce many flowers on long, pendulous panicles while female trees produce either solitary flowers of clusters of a few flowers which are yellow-green in color. Hermaphrodite trees produce bisexual flowers. The papaya fruit is a large fleshy berry with smooth green skin that ripens to yellow or orange. The flesh of the fruit is thick and succulent and ranges in color from yellow to red or orange. The fruit contains many black wrinkled seeds. Papaya trees range in height from 2–10 m (6.6–33 ft) and can live for up to 25 years. Plantations are usually replaced every 3 years to ensure maximum productivity. Papaya may also be referred to as pawpaw and is believed to originate from the Caribbean region on Central America.
Ripening papaya fruit
Papaya flesh and seeds
Papaya fruit developing
Papaya tree
Papaya leaf
Male papaya flowers
Papaya fruits on tree
Papaya leaf
Papaya tree
Uses
Papaya fruits are commonly eaten fresh. The may also be processed into jams, jellies and juices are dried and candied. Green fruits and young leaves can be cooked and eaten as a vegetable.
Propagation
Basic requirements
Papaya is a tropical plant and will grow optimally at temperatures between 21 and 33°C (69.8–91.4°F) in areas with no frost. Papaya can be grown in a range of soils as long as there is adequate drainage but will grow optimally in light, well-draining soils with a pH between 5.5 and 6.5. Papaya requires well distributed rainfall of about 4 inches per month. In areas with low rainfall, trees should be provided with supplemental irrigation. Trees are very sensitive to flooding and water-logged soils should be be avoided. Papaya is also sensitive to high winds and the tall trees can be easily toppled. Windy areas should be avoided for planting.
Propagation
Papaya is propagated from seed due to the labor involved in producing cuttings. Seeds are usually sown in small containers or nursery beds in sterilized soil. It is usual to sow 3–4 seeds per container and seeds can take 3–4 weeks to germinate depending on temperature.. Seedlings are transplanted after approximately 2 months when the reach approximately 20 cm (8 in) in height and possess 3–4 leaves. Seedlings are commonly planted on hills or ridges to aid drainage and should be spaced 2–3 m (6.6–9.8 ft) apart.
General care and maintenance
Papaya seedlings are very susceptible to competition from weeds and the areas around the trees should be kept weed-free. A layer of mulch around the plants can successfully suppress weeds. Papaya requires regular fertilizer applications to meet the nutrient requirements for fruit production. In commercial plantations, fertilizer is usually applied 2–4 times per year. In the home garden, the addition of 1/4 cup of a balanced fertilizer every 14 days is usually sufficient. As the trees mature, the amount of fertilizer should be increased. When trees reach 7 to 8 months, 1–2 lbs of a complete fertilizer should be provided every 2 months. Papaya trees should be watered regularly, particularly during hot, dry periods. Papaya trees do not require pruning but it is good practice to remove any dead leaves from the tree.
Harvesting
Papaya fruits generally require 22–26 weeks to mature. The fruits can be picked when 1/5 of the fruit surface has turned from green to yellow but leaving them on the tree longer will increase the sugar content of the fruit. Fruit can be twisted or snapped from the tree or cut using a sharp knife.
References
CABI Crop Protection Compendium. (2008). Carica papaya (papaw) datasheet. Available at: http://www.cabi.org/cpc/datasheet/13392. [Accessed 03 March 15].
Paid subscription required.
Crane, J. H. Papaya growing in the Florida home landscape. University of Florida IFAS Extension. Available at: https://edis.ifas.ufl.edu/pdffiles/MG/MG05400.pdf. [Accessed 03 March 15].
Free to access.
Nishina, M., Zee, F., Ebesu, R., Arakaki, A., Hamasaki, R., Fukuda, S, Nagata, N., Chia, C. L., Nishijima, W., Mau, R. & Uchida, R. (2000). Papaya production in Hawaii. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Available at: http://www2.ctahr.hawaii.edu/oc/freepubs/pdf/F_N-3.pdf. [Accessed 03 March 15].
Free to access.
Ploetz, R. C., Zentmyer, G. A., Nishijima, W. T., Rohrbach, K. G. & Ohr, H. D. (eds) (1994). Compendium of Tropical Fruit Diseases. American Phytopathological Society Press. Available at: http://www.apsnet.org/apsstore/shopapspress/Pages/41620.aspx.
Available for purchase from APS Press.
Common Pests and Diseases
Diseases
Category : Fungal
Anthracnose and charcoal spot
Colletotrichum gleosporoides
Charcoal spot on papaya fruit
Anthracnose symptoms on papaya
Anthracnose lesions on papaya fruit
Anthracnose lesions on papaya fruit
Charcoal spot
Anthracnose lesions on papaya fruit
Anthracnose lesions on papaya fruit
Anthracnose lesions on papaya fruit
Anthracnose symptoms on papaya
Anthracnose lesions on papaya fruit
Anthracnose lesions on papaya fruit
Symptoms
Small water-soaked lesions of fruit during ripening; circular sunken lesions with light brown margins.
Cause
Fungus
Comments
Management
Appropriate protective fungicides should be applied; dipping fruits in hot water at 48°C for 20 minutes reduces the incidence of the disease.
Black rot
Mycosphaerella caricae
Black rot symptoms
Symptoms
Black sunken rot on young fruits originating from stem end or contact with a leaf; young fruit withering and dropping from plant; small, brown sunken lesions with light brown margins on ripening fruit.
Cause
Fungus
Comments
Management
Appropriate protective fungicides should be applied; dipping fruits in hot water at 48°C for 20 minutes reduces the incidence of the disease.
Black spot
Asperisporium caricae
Black spot of papaya
Infected fruit
Black spot symptoms
Black spot of papaya (Asperisporium caricae) infected fruit
Symptoms of black spot on papaya fruit
Black spot of papaya
Black spot infected fruit
Black spot symptoms
Symptoms of black spot on papaya leaf
Symptoms of black spot on papaya fruit
Papaya (Carica papaya): Black spot, caused by Asperisporium caricae
Symptoms
Close up of black spot of papaya
Symptoms of black spot on papaya leaf
Symptoms
Circular water-soaked or brown lesions on older leaves; centers of lesions become bleached as they mature; leaves curling and turning brown; raised lesions on trunks; sunken circular lesions on fruit.
Cause
Fungus
Comments
Management
Disease may require applications of appropriate fungicides for adequate control.
Cercospora black spot
Cercospora papayae
Cercospora sp. on papaya
Symptoms of Cercospora black spot on papaya
Symptoms
Tiny black dots on fruit which enlarge to 3 mm across; spots are slightly raised and although indistinct on unripe green fruit, become visible on ripening to yellow; lesions on leaves are irregular in shape and gray-white in color; if infestation is severe, leaves may turn yellow and necrotic and drop from plant.
Cause
Fungus
Comments
Management
Applications of appropriate protective fungicides at intervals of 14 to 28 days provide satisfactory control of the disease.
Powdery mildew
Oidium caricae-papayae
Other fungi species
Upper leaf surface
Lower leaf surface
Infected fruits
Chlorotic lesions
White mycelial growth on lower leaf surface
Mycelial growth on upper leaf surface
Powdery mildew symptoms
Symptoms on upper leaf surface
Chlorotic lesions due to powdery mildew infection
Symptoms on upper leaf surface due to powdery mildew infection
Symptoms
Symptoms on lower leaf surface
Infected fruits
White mycelial growth on papaya fruit
Powdery mildew of papaya caused by Oidium caricae
Symptoms
Infect all parts of tree. The infected leaves show white mycelial growth commonly on under surface , particularly near leaf veins. Some time white mycelial growth can also seen on upper leaf surface. The infected area becomes light green and chlorotic (lesions) with dark green margin.
Cause
Fungus
Comments
Management
Remove the infected parts and dispose them properly. Avoid irrigating the trees by sprinkler. Provide proper nutrition to trees to withstand powdery mildew infection. If the disease is severe, apply suitable fungicides.
Category : Bacterial
Bacterial canker and decline
Erwinia spp.
Symptoms
Angular water-soaked lesions on leaves; lesions coalesce and spread along leaf veins; witling leaves, particularly at top of canopy; water-soaked lesion and cankers on stem; cankers girdle stem and cause plant to collapse; small water-soaked lesions on green fruit.
Cause
Bacteria
Comments
Internal yellowing
Enterobacter cloacae
Symptoms
Flesh of ripe fruit discolored yellow; discolored areas soft with spreading margins; rotting odor.
Cause
Bacterium
Comments
Management
Dipping fruits in hot water at 48°C for 20 minutes reduces the incidence of the disease and is currently the only method of control.
Category : Viral
Bunchy top
Likely caused by Rickettsia bacteria
Symptoms
Chlorosis of young leaves; water-soaked spots on petioles and stems; petioles rigid, horizontal and shortened; thickened leaf blades that cup downward; internodes shorten and growth stops resulting in a bunchy appearance to the plants.
Cause
Bacteria
Comments
Management
Use of tolerant varieties of papaya is currently the only method of control recommended.
Papaya ringspot
Papaya ringspot virus (PRV)
Papaya Ringspot Virus symptoms
Papaya ringspot symptoms on fruit
Foliar symptoms of papaya ringspot
Papaya ringspot symptoms on unripe fruit
Papaya ringspot infected plant
Foliar symptoms of papaya ringspot
Papaya ringspot symptoms on fruit
Papaya ringspot symptoms on unripe fruit
Papaya Ringspot Virus (Potyvirus PRSV) infected leaves
Papaya ringspot symptoms on fruit
Foliar symptoms of papaya ringspot
Papaya ringspot symptoms on unripe fruit
Symptoms
Dark green rings on fruit which may be slightly sunken and become less distinct as the fruit ripens; fruits may have uneven bumps; leaves often exhibit a bright yellow mosaic pattern and new leaves are small and plant growth is stunted.
Cause
Virus
Comments
Management
Infected plants should be removed and destroyed to prevent spread of the virus; new planting materials should be free of the virus; intercropping papaya with a non-host such as corn can help to reduce the incidence of the disease in papaya orchards by providing aphid vectors with an alternative feeding site.
Category : Oomycete
Phytophthora fruit rot (Stem rot)
Phytophthora palmivora
Fruit rot due to Phytopthora
Phytophthora infected tree
Symptoms of Phytophthora infection on papaya fruit
Symptoms of Phytophthora infection on papaya fruit
Phytophthora stem rot affected papaya tree
Phytophthora infected fruit
Phytophthora on papaya fruit (after experimental inoculation with pathogen)
Symptoms of Phytophthora infection on papaya fruits
Phytophthora fruit rot
Stem rot symptom
Symptoms of Phytophthora infection on papaya fruit
Symptoms
Water-soaked lesions on unripe fruit that oozes latex; withering fruit; water-soaked lesions on leaf scars of fruit bearing stem; mature fruit covered in white mycelium.
Cause
Oomycete
Comments
Management
Disease can be controlled through the use of appropriate protective fungicides such as mancozeb or copper sulfate; root rot in seedlings can be prevented by planting in holes filled with soil in which papaya has never been grown - by the time the roots extend out of the added soil the plant is no longer susceptible to the disease.