Some components of the air‐spora in Jamaican banana plantations

Abstract

SUMMARYThe air in several Jamaican banana plantations was sampled from July 1960 to September 1961 with an automatic volumetric spore trap. In dry weather, many fungi showed typical diurnal periodicity. Group I fungi (Deightoniella, Nigrospora, Cordana, Corynespora, Zygosporium and Zygophiala) first appeared shortly after 06.00 hr., reached a peak before 09.00 hr. and then showed a rapid fall. Group II fungi (Cladosporium, Alternaria, Curvularia, Cerebella, Pithomyces, Periconiella, Memnoniella, Ustilago and others) and pollens had peak concentrations between 09.00 and 14.00 hr. Groups I and II formed the majority of the spore catch during daylight, but they were practically absent between 20.00 and 06.00 hr. Group III fungi (represented chiefly by ascospores, especially of Leptosphaeria spp., basidiospores and splash‐dispersed types) first appeared near 20.00 hr., attained a maximum between midnight and 06.00 hr. and a minimum during daylight. In dry weather, Cladosporium conidia accounted for 23% of the total catch; coloured fusiform spores for 18%; coloured basidiospores for 16%; unclassified minute spores (including Sporobolomyces) for 14%; and Deightoniella only 0.2%.During rain, the typical dry‐air‐spora decreased and was replaced to varying extents by group III ascospore types and splash‐dispersed spores. When, after rain, the plantation dried out during daylight, group III fungi decreased while groups I and II briefly reappeared before the typical night‐time flora developed. When rain was continuous during daylight, groups I and II were rare; ascospores and splash‐dispersed spores dominated the traces. All fungi occurred in low concentrations during heavy rain, periods of drought and strong wind. With rain or under‐tree irrigation or both, the following days had varying increases of all group I fungi and certain group II fungi, probably because favourable humidity conditions caused increased sporulation.