Many tennis players know that bananas are a fast-food which is actually good for you. They eat them between sets for a quick but sustained burst of energy. Bananas are rich in carbohydrate, potassium and vitamins, including A, C, and B6. They are a good source of dietary fibre and are fat-free.
But, bananas are far more than that: 98% of bananas are grown on small farms in developing countries and are a staple food of more than 400 million people living in the tropics.
The United Nations Food and Agriculture Organisation (FAO) ranks bananas as the world’s fourth most important crop after the major cereals.
In India bananas are called "kalpatharu", meaning "herb with all imaginable uses". Bananas are a surprisingly versatile crop, not just as a food, but with many other uses, including medicinal applications and a source fibre from the leaves. Banana plants are also grown to support the production of many other crops which need shade including cocoa, coffee, peppers and nutmeg.
Banana plantations can be a fragile environment and soil, water and biodiversityDescription The variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity (IUCN, UNEP and WWF, 1991). Authoritative On-line References and Resources http://earthtrends.wri.org/ EarthTrends is a comprehensive online database, maintained by the World Resources Institute, that focuses on environmental, social, and economic trends. Statistics on biodiversity indicators are available. all need special care. Bananas need protecting from weeds, pests and diseases, which flourish if unchecked in tropical climates so integrated pest management (IPMDescription A decision support system for crop protection which focuses on long-term prevention or suppression of pest problems with minimum impact on human health, the environment, and non-target organisms. IPM takes into consideration all available pest control techniques and tactics (cultural, mechanical, biological, chemical). IPM emphasizes the growth of healthy crops for better productivity with the least possible disruption to agroecosystems. Authoritative On-line References and Resources http://www.ipmcenters.org "The USDA's National Site for the Regional IPM Centers' Information System provides information about US commodities, pests and pest management practices, people and issues.") approaches are widely used to ensure that crops are protected in a sustainable way. Weed management is central to IPM systems and the non-selectiveDescription A chemical product used for eliminating all types of weeds (annual and perennial grasses and broadleaved weeds). Authoritative On-line References and Resources http://www.weeds.iastate.edu/ An invaluable source of contemporary information about herbicides and weeds from Iowa State University. herbicide paraquat has a key role.
Paraquat is an essential tool in banana plantations
All green parts of plants may be damaged by paraquat because it works through interfering with photosynthesis, a fundamental plant process. Paraquat’s mode of action means that a very broad spectrum of weeds are controlled. However, although it is termed ‘non-selective’, paraquat is safe to banana crops for two reasons. Firstly, it is deactivated on contact with the soil meaning that it cannot move to roots and be taken up into plants.
You can read more about paraquat’s unique soil properties here.
Secondly, it is sprayed around the crop plants and even if small amounts of paraquat land on crop leaves there is little or no damage because paraquat does not move through plants systemically like the alternative non-selective herbicide glyphosate.
Intensive use of glyphosate has caused new weed problems as species less well controlled have ‘shifted’ to become more dominant and some species have evolved biotypes which are resistant to glyphosate. Using paraquat as an alternative non-selective herbicide, with a different mode of action, is helping to avoid problems of weed shifts and resistance.
Paraquat is very fast acting and rainfast, unlike glyphosate. Weeds sprayed in the morning will often show symptoms by the afternoon, making it easy for spray operators and plantation managers to see which areas have already been sprayed. This holds even if rain falls within 15-30 minutes, making it possible to spray for longer before rain is expected.
A video showing paraquat’s unsurpassed speed of action can be viewed here.
In perennial plantation crops such as bananas, emphasis is on the management of weeds rather than their permanent removal. This is because maintaining a particular balance of weeds in the plantation flora is important for sustainability by integrated pest management techniques and minimising soil erosionDescription Displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement. Authoritative On-line References and Resources http://soilerosion.net/ This site brings together reliable information on soil erosion from a wide range of disciplines and sources. It aims to be the definitive internet source for those wishing to find out more about soil loss and soil conservation. though the anchoring effect of plant roots.
Paraquat has a very robust environmental profile. It does not leachDescription The natural process by which water soluble substances are carried downward through the soil into groundwater. and is degraded in soil. Further details of paraquat’s safety to the environment, spray operators and consumers can be found by visiting the different sections of the Paraquat Information Center or referring to the Paraquat Fact Sheet.
You can read more about the benefits of using paraquat here.
Global Production of bananas
Bananas (Musa paradisiaca L.) are herbaceous plants, not trees, despite having an apparent ‘trunk’ and typically growing up to 6 m tall. The ‘trunk’, or pseudostem, comprises the tightly rolled leaf sheathes which arise from a bud on an underground storage organ called a corm. About 30 leaves emerge from the bud over 7-8 months before flowering. The large flower ‘spike’ has separate male and female flowers.
After pollination banana fruit set at the base of the female flowers, clustered in several ‘hands’ on each bunch. Botanically, the banana fruit is a berry, but commercial cultivars have no seeds, being sterile.
After 2-3 months, bunches weighing typically 20-25 kg are ready for harvest. Each banana shoot only flowers once before dying back, but suckers are sent out underground from the main stem to produce daughter plants which will provide the next harvest.
There are many types of banana varieties, many of which would surprise western consumers used to the ubiquitous Cavendish desert variety found in supermarkets. Others include Red Cubans (or Colorados) which come from Ecuador and have brownish-red skins, Lactatans from the Philippines which are very aromatic, and Manzanos and Burros which have faint flavours of apple and lemon, respectively. Other exotic varieties are generally only consumed locally because they do not store well or have thin skins and are easily damaged
Banana production and trade
Where are bananas grown?
Bananas are grown in tropical climates where heat, sunlight, and water are plentiful. Average temperatures of around 25oC and monthly rainfall of about 10 cm, with only short dry seasons, are necessary.
Wind can be a problem for bananas. Leaves may be shredded or broken and strong winds can topple plants unless they are propped, especially when bearing fruit.
Best soils are free-draining and rich in organic matter, ideally with a slightly acid pH.
Easy access to roads and railway lines is important for rapid distribution of the harvested fruit.
Production and trade
Bananas are grown in over 130 countries, but production is highly concentrated. The top ten countries account for more than 75% of the world harvest. Over the past decade global production of bananas has increased by over 40%. Some of the most marked changes have occurred in Asia. Production has increased by 83% in China, 56% in the Philippines and 89% in India. The area of bananas grown in China increased by 47% in this period and yields improved from 20.8 to 25.9 tonnes/ha. The average yield of bananas in the world in 2008 was 19.3 tonnes/ha, but the best yields are many times this, particularly from Central American countries, e.g. typically around 50 tonnes/ha in Costa Rica.
Banana production is characterised by large producers with essentially domestic use of their crop such as India, China and Brazil, and large exporters. Latin America and the Caribbean supply more than 80% of exports. Many of these countries are highly dependent on bananas for a significant part of their foreign income, e.g. up to 20% for some.
Although less than 20% of banana production is exported, this makes it one of the most valuable fruit in world trade, worth nearly $6 billion per annum and second only to the total for all citrus fruits combined.
There are distinctive patterns of trade between exporting regions and importing countries. These are dictated by trade agreements, transportation costs and time as regards storage and ripening. The major importers are the European Union (39%), the US (26%) and Japan (7%). Imports to Europe come particularly from Ecuador, Columbia, Costa Rica, the Caribbean and West Africa, with some national production particularly in the Canary Islands (Spain). The North American market is supplied mainly by countries in Central and South America. Japan imports bananas chiefly from the Philippines and Ecuador.
Bananas’ many uses
Bananas, of course, are a delicious ready-packaged meal usually eaten raw, but bananas and plantains (the names are actually used interchangeably in various parts of the world) may also be eaten boiled, steamed, mashed and rolled into balls as ‘foutou’, grilled, roasted or fried; a flour for cakes and biscuits is made in the tropics; and in the Philippines, banana ketchup is popular. A beer made from the juice of ripe fruit is popular in central Africa. Animals, especially pigs, are reared on surplus fruit.
Bananas have several medicinal uses. Eating a banana can help digestion thanks to the high vitamin A content, and ripe fruit are reported to be used to treat asthma and bronchitis. Even the peel is useful as a poultice or emergency wrap for wounds because the inside of the peel reputedly has anti-septic properties and has been claimed to remove warts.
There are a number of industrial uses of bananas:
- Fibre from banana leaves makes strong paper and is used to make bank notes and tea bags. ‘Manila hemp’ is the fibre from the leaves of the ‘Abaca’ variety of banana, used to make sacks and rope
- Leaves are used in food preparation and storage, and for thatching
- A starch-based glue extracted from pseudostems is used in making banana packaging.
- Banana sap can be used as a dye
Sustainable banana production
Banana plantations should be replanted at least every 7-10 years as yields are by then declining. All remains of the previous crop have to be eradicated by digging out or destroying with a systemic herbicide to prevent carryover of pests and diseases. After tilling the soil a legume such as Calopogonium spp., Puereria spp. or Stylosanthus spp. are planted. These are dug-in as a green manure after a couple of years before planting the banana crop. Most bananas are clones and a new crop is planted using either pieces of corm containing a bud, known as ‘bits’, or suckers aged about 4 months from well-established plants. The latter are trimmed to 50 cm, and dipped into a solution of potassium permanganate before planting in a hole filled with compost. Potassium is a particularly important nutrient for bananas and several applications, together with nitrogen, are made each year. Phosphorous and lime are applied less frequently.
The new parent plants are spaced more widely if the plantation is on a longer re-planting cycle or if it is to be inter-cropped eg with rubber or oil palm. These crops are slow to mature and, being much sooner to reach harvest, bananas allow some quick return. Cocoa is another species which bananas are grown alongside. Young cocoa benefits from the shade that bananas provide.
Four months after planting the parent plants suckers are removed to leave one daughter shoot, ideally growing in the crop row. This will establish the cycle of new daughter plants growing to provide successive harvests. Older withered and drooping leaves are cut off because they would interfere with spraying, shade the suckers, cause blemishes on the fruits, harbour pests and diseases, and constitute a fire hazard. As the fruit grow, the developing bunches are propped or the plants are tied back to support the weight. The fruit are covered to enhance development and protect from blemishes.
Banana bunches are ready for harvest about 10 weeks after the first flowers open. The fruit are fully grown, but still green. Careful handling is needed and light must be avoided so as not to induce ripening while being transported to the packing shed. Bananas are generally ripened under controlled temperature and humidity in storage rooms and exposed to ethylene gas.
Pests and diseases
Insect pests include the banana weevil (Cosmopolites sordidus) which lays eggs in the base of shoots. When the larvae hatch they eat out the heart of the shoot. Others include aphids (which cause bunchy top disease), thrips and scale insects. Nematodes are a very common and serious problem, feeding off the roots and corms. Numerous species include Pratylencus spp. and Meloidogyne spp. They often provide an entry point for soil borne fungi, eg Fusarium. In the Philippines, for example, common nematode pests are Radopholus similis and Helicotylenchus spp.
Fungal diseases include Panama disease (Fusarium oxysporum f. sp. cubense) which is a soil borne wilt which makes leaves break. In the 1950s, Panama disease all but wiped out the then ubiquitous Gros Michel variety. Its successor, the Cavendish banana, originally resistant, was attacked by a mutation in 1992 which destroyed the Malaysian crop. At present this strain is confined to Asia, but there are fears of it reaching Latin America and the Caribbean. Another serious disease is black sigatoka (Mycosphaerella fijiensis var. difformis) which turns leaves a mottled yellow, brown and black. This disease has reduced yields by 40% in Uganda.
Moko disease is a bacterial rot caused by Pseudomonas solanacearum, which has seriously reduced production in Colombia. It is transmitted by insects, machetes and other tools, plant residues, soil, and by root-to-root contact. In Colombia, there are several weed species which carry the disease and can infect bananas.
Tropical climates with ample sunshine, heat and moisture mean that weeds thrive and may compete with crops for space, water and nutrients, and shade the crop plants, especially when they are young. A large number of weeds, both annualsDefinition Weeds that complete their life cycle within one growing season, or year. From seed to flowering to seed before the year ends. Authoritative On-line References and Resources The International Weed Science Society represents individual associations around the world. and perennialsDescription Weeds that return year after year. Some die back in the winter but their roots remain alive and shoots reappear in spring; some don't die back and grow in size and stature the next season. Authoritative On-line References and Resources The International Weed Science Society represents individual associations around the world. infest banana plantations and weed control is very important in the early months after planting before plants produce enough leaf canopy to shade out weeds.
Crop safety is especially important while controlling weeds in bananas because the next harvest cycle depends on a new crop of daughter suckers. These are very susceptible to being killed by systemic broad-spectrum herbicides based on glyphosate. Paraquat can be used safely around parent and daughter plants with no fear of accidental spray drift damaging either generation.
After many years of experience, major banana companies have adopted spray programs involving precision application of paraquat every four weeks as a spot spray. This approach means that only low rates of paraquat (0.5 l/ha or less) are needed to control small weeds which are easily removed before they compete with the crop or flower and return weed seeds to the soil.
CASE STUDY: Paraquat maintains biodiversity in the banana plantations of Costa Rica
Syngenta (as its legacy company Zeneca), collaborated with EARTH (Escuela de Agricultura de la Region Tropical Humeda), Del Monte and Dole, and showed how biodiversity can be maintained in commercial banana plantations in Costa Rica. Banana farmers there use paraquat to manage plantation weeds while reducing soil erosion and maintaining biodiversity including fish, amphibians, reptiles and birds.
A well-managed source of water is critical for banana production. Bananas need a constant supply of water – at least 160 mm/month – but cannot stand water-logged soil. In the tropical rainy season, some months may have more than 1000 mm excess rainfall. In commercial plantations excess water is removed by an elaborate system of drainage channels which also ensure a supply of water in the dry season. The banks of these ditches are a haven for vegetation and wildlife.
For sustainable production it is important that vegetation is controlled so as not to reduce the yield of bananas harvested while maintaining the biodiversity in the plantation. Keeping habitats for predators of insect pests, for example, is a key aim. Paraquat is an ideal herbicide in this respect because its non-systemic and non-residual action means that it only controls weeds targeted by spray operators. Paraquat does not move through soil so cannot be taken up by the roots of non-target plants, and only controls top-growth. So, the root system of perennials and large plants remains intact to provide valuable additional structure to the soil which minimises erosion on vulnerable slopes and helps prevent soil clogging the ditches. Maintaining a presence of non-competitive vegetation keeps a source of new organic matter, essential for healthy soils. Because paraquat is extremely tightly bound to soil particles immediately on contact, it cannot leach into groundwater or contaminate water in the channels from any surface run-offDescription The occurrence of surplus liquid (like rain) which originates up-slope and is collected beyond the ability of the soil to absorb it. The surplus liquid then flows away over the surface to reach the nearest surface water (pond, lake, river). Authoritative On-line References and Resources US Geological Survey's Water Science School.