Pyricularia grisea(Cooke) Sacc. causing pitting disease of bananas in Central America

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Abstract
SUMMARY: Dark‐coloured, depressed spots (‘pits’), up to 10 mm. in diameter, are recorded on Giant Cavendish banana fruits in Costa Rica. Pits first appear in the field, usually on almost mature bunches, and increase in numbers during cold storage and ripening. Symptoms are identical with those of ‘Johnston fruit‐spot’ and ‘pitting disease’ described by earlier workers. Disease is maximal during and for a short time after heavy rainfall.Pyricularia griseawas consistently isolated from typical pits, and disease was reproduced by inoculating fruit in the field with conidia of P.griseafrom pure culture. Conidia germinate after 1–2 hr. in a film of water on the peel of immature fruits. An appressorium is formed and there is some evidence that this produces an infection hypha which, in the first instance, penetrates the cuticle but not the epidermis cell wall. In most cases, there is no evidence of further penetration until the fruit is ready for harvest, or until after harvest. The fungus then resumes activity and invades the epidermis and underlying tissues to cause a pit. Latency in P.griseais compared with that inGloeosporium musarum.