Panama disease, a Fusarium wilt

Fusarium wilt

Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. The pathogen that causes Fusarium wilt is Fusarium oxysporum . The species is further divided into forma specialis based on host plant.-Hosts and symptoms:The fungal pathogen Fusarium...

, is a banana

Banana

Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....

 plant disease

Phytopathology

Plant pathology is the scientific study of plant diseases caused by pathogens and environmental conditions . Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants...

 caused by the fungus

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 Fusarium oxysporum

Fusarium oxysporum

Fusarium oxysporum Schlecht. as emended by Snyder and Hansen comprises all the species, varieties and forms recognized by Wollenweber and Reinking within an infrageneric grouping called section Elegans...

. The fungus attacks the roots of the banana plant. The disease is resistant to fungicide

Fungicide

Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

 and cannot be controlled chemically.

History

Gros Michel

Gros Michel

Gros Michel, often known as Big Mike, is an export cultivar of banana, and was until the 1950s the main variety exported to the United States.-Taxonomy:Gros Michel is a triploid cultivar of the wild banana Musa acuminata, belonging to the AAA group....

 or 'Big Mike' was an early export cultivar

Cultivar

A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...

 of banana. This cultivar was wiped out by Panama disease in the 1950s

1950s

The 1950s or The Fifties was the decade that began on January 1, 1950 and ended on December 31, 1959. The decade was the sixth decade of the 20th century...

. The disease first appeared in Suriname

Suriname

Suriname , officially the Republic of Suriname , is a country in northern South America. It borders French Guiana to the east, Guyana to the west, Brazil to the south, and on the north by the Atlantic Ocean. Suriname was a former colony of the British and of the Dutch, and was previously known as...

, then made its way to the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

, and, by the 1920s, to Honduras

Honduras

Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...

, the world's largest producer of bananas at the time. Although there are many banana cultivar

Cultivar

A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...

s, Gros Michel was especially suitable for export to non-tropical nations. A search for a substitute located the Vietnamese

Vietnam

Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 Cavendish

Cavendish banana

The Dwarf Cavendish banana is a banana cultivar originally from Vietnam and China. It became the primary replacement for the Gros Michel banana in the 1950s after crops of the latter were devastated by the Panama disease. The name 'Dwarf Cavendish' is in reference to the height of the pseudostem,...

 cultivar, which is resistant to the disease. However, more care is required for shipping the Cavendish banana, and its quality compared to Gros Michel is debated.

Recently, a new strain called 'tropical race four Panama disease'

Fusarium oxysporum f.sp. cubense

Fusarium oxysporum f.sp. cubense is a fungal plant pathogen that causes Panama disease of banana , also known as fusarium wilt of banana.-Overview:...

 has begun to attack Cavendish banana plants in south Asia

South Asia

South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...

. Given the high volume of modern international trade

International trade

International trade is the exchange of capital, goods, and services across international borders or territories. In most countries, such trade represents a significant share of gross domestic product...

, banana producers expect this strain to spread through Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 and into South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 and the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

.

Plant breeders and geneticist

Genetics

Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

s are trying to develop new cultivars that are resistant to this new strain of Panama disease. Unfortunately, such efforts are progressing slowly because the triploid banana cultivars selected for human consumption are seedless and reproduce asexually

Asexual reproduction

Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...

, which decreases genetic variation

Gene pool

In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...

and makes breeding difficult.

Resources

• International Network for the Improvement of Banana and Plantain (INIBAP)
• Can This Fruit be Saved? (discusses the disease threat to banana crops)