Seasonal changes in the apple phylloplane microflora

Abstract

Abstract Microbial populations in the phylloplane of unsprayed ‘Dougherty’ apple trees were estlfllated by maceration-dilution platmg and spore fall methods during two growing seasons in Auckland, New Zealand. The dense microflora within unopened flower buds declined rapidly as the buds opened and the rosette leaves unfurled; some species of the bud microflora disappeared from the phylloplane within a few days, and new species derived from the air spora became established. Newly unfurled shoot leaves did not have a distinctive microflora derived from the vegetative buds; they supported a sparse microflora which included air spora-derived species. Population densities declined during leaf expansion, then increased when leaves attained full size. Mould populations were evenly distributed between the two leaf surfaces, and increased only slightly during summer. In March, Tilletiopsis minor Nyland increased markedly, predominantly on the abaxial surface, and maintained a high population density until leaf fal...