Spore Dispersal in Pyricularia grisea (Cooke) Sacc.

Abstract

Pyricularia grisea is probably best known in relation to ‘blast’ disease of rice. Some workers have considered this fungus to be the causal organism, but others ascribe the disease to a distinct species. P. oryzae Cav.¹. P. grisea is associated with ‘pitting’ disease of Cavendish bananas in Brazil, Trinidad and Australia^2–6. Pitting is commonest on the finger-stalks and cushions of the large proximal hand of the bunch and, in advanced stages, may result in finger-dropping. Groups of spots or pits may also be scattered over the fruit surface. In attempting to explain the distribution of pits on the bunch, Wardlaw⁴ suggested that P. grisea “may be widely and abundantly disseminated by wind”; however, this was not investigated further. No conidia of P. grisea were detected during an earlier survey of the air-spora of Jamaican banana plantations⁷; but in recent aerobiological studies appreciable spore counts were recorded and these are the subject of the present communication.