The Case Studies - Black Sigatoka

Taxonomic Name: Mycosphaerella fijiensis
Common Names: Black leaf streak
Ecological Category: Fungus
Main impacts: Agricultural

Description

Black Sigatoka, or black leaf streak, is a widespread disease of bananas, caused by the fungus Mycosphaerella fijiensis. It is one of the most destructive of all the leaf diseases of bananas.

It affects leaves, reducing the photosynthetic area of the plant and subsequent banana yields. It was first identified in Fiji, but is found in most banana producing areas of the world.

Black sigatoka doing its thing in Malawi, East Africa.
Black sigatoka infected bananas

Habitat

Black sigatoka spores form readily during tropical and sub-tropical summers or under conditions of high humidity and rainfall.

Current Distribution

Mainland Australia is currently free of Black sigatoka, but since 1981 several separate incursions of Black Sigatoka have taken place in separate locations of Cape York, including Bamaga, Weipa and Tully. On each occasion the diseased plants have been eradicated, and the disease is yet to spread outside of Cape York.

Black Sigatoka is endemic in parts of the Torres Straits which lies between Papua New Guinea and Cape York Peninsula.

Distribution of Black Sigatoka
Soruce: Agriculture WA Factsheet No 14/2000

Dispersal / Reproduction

The spores of Black Sigatoka are primarily spread via rainwash or splash. Infection occurs on the youngest leaves of the plant during and older leaves are generally not readily infected.

Impacts

Black sigatoka causes destruction of banana leaf tissue, which affects the photosynthetic capabilities of the plant and can reduce yields by up to 50%. Black sigatoka is one of the main factors responsible for the decline in banana export industries in South Pacific nations.

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