First report of black sigatoka disease (causal agent Mycosphaerella fijiensis) from Trinidad

In October 2003, first reports of damaging leaf lesions on 'horse' plantains were investigated from Coromandel Village, Cedros in St Patrick county (Fig. 1). Symptoms characteristic of black sigatoka disease, also known as black leaf streak, were observed. The first leaf streaks were frequently found on leaves as young as leaf 2, indicating that plants were severely infected. Later the streaks became more conspicuous and lead to withering and death of leaves (Fig. 2, 3 & 4) (Carlier et al., 2000). A fungus was consistently recovered from lesions and was identified as Mycosphaerella fijiensis; the cause of black sigatoka disease. Conidiophores arise either singly or in groups of 2-3, mainly from stomatal openings, were pale brown, rarely branched, mostly 0-3 septate, were 25-80 mm long, with conspicuous conidial scars. Stroma were absent. Conidia are obclavate, tapering towards the apex, 20-132(72) x 2.5-5mm, straight or curved, mostly 4-6 septate, with a round base and thickened hilum. Conidia production is predominantly on the lower leaf surface at the early streak stage. This identification was confirmed by the Global Plant Clinic of CABI Bioscience in Egham, UK.

Farmers' reports suggest that the disease may have been present in Trinidad since 2002. A detailed survey in an approximately five kilometre radius from the first site revealed three plantain fields severely infected. Little economic yield is expected from the affected areas, as the disease leads to poorly developed fruit that ripens prematurely. Symptoms of black sigatoka were also found, albeit at low levels of incidence and in conjunction with predominantly yellow sigatoka lesions, on bananas in more distant areas of St. Patrick and Victoria. No symptoms were observed on 'moko plantains'. A survey of St. George, St. Andrew, St. David and Caroni in the north of Trinidad revealed no evidence of black sigatoka.

This is the first confirmed report of black sigatoka disease from Trinidad, though it has been present in Venezuela since 1991 (Carlier et al., 2000). Local reports indicate possible introduction through the clandestine importation of banana and plantain propagation material from the South America mainland and the use of trash leaves as fruit packaging material. Black sigatoka has been present in the Caribbean region since 1972, when it was first detected in Honduras (Carlier et al., 2000). Production of bananas and plantains in Trinidad is carried out by small-scale, subsistence farmers with limited access to crop protection inputs. If M. fijiensis was to become well established in Trinidad, it could spell the collapse of the local banana and plantain industry.