THE RELATIVE IMPORTANCE OF COLLETOTRICHUM-MUSAE AS A CROWN-ROT PATHOGEN ON WINDWARD ISLAND BANANAS

Low numbers of conidia of Colletotrichum musae (10-50) applied directly to the surface of freshly cut banana crowns caused extensive rot development. At least 20 times more conidia of Fusarium pallidoroseum were required to cause comparable levels of crown rot. Examination of the relative pathogenicity of the major fungal species involved in development of crown rot, C. musae, F. pallidoroseum, Fusarium moniliforme, F. moniliforme var. subglutinans, and Botryodiplodia theobromae, using a standard inoculum of 2 x 10(3) conidia per crown, showed C. musae to be the most aggressive species. C. musae produced a distinctive soft, dry fibrous rot while the fruit was still green, and on ripening further rotting, softening and blackening of crown tissues occurred. The other crown-rot pathogens tested did not rot green fruit. Fruit inoculated with C. musae and held for 0, 1, 2 and 3 days at ambient temperature before ripening sustained increasingly more severe crown rot. C. musae was isolated with increasing frequency from rotting tissue the longer the period under ambient conditions. Crowns which had been inoculated with F. pallidoroseum and held for a comparable period did not display such extensive rot development although the pathogen was very frequently isolated from the tissue.