Rainwater dispersal of Botryosphaeria conidia from infected grapevines

Abstract

Dispersal of spores was investigated for the Botryosphaeria species that are responsible for dieback in grapevines. Trapping for spores was carried out in a Canterbury vineyard during May 2008-April 2009 to investigate spore availability during the year. No spores characteristic of the Botryosphaeriaceae were collected on Vaseline® slides, which were considered suitable for wind dispersed spores, although spores of other fungi were collected. However, traps that collected rainwater runoff yielded conidia of the Botryosphaeriaceae. In haemocytometer counts of spores they were initially identified by morphology, and subsequently confirmed by PCR of rDNA followed by DNA sequencing. During the trapping period, 59.8% of the total Botryosphaeriaceae caught were Neofusicoccum spp. and 40.2% were Diplodia spp. These were present throughout the entire year, with most abundant conidia being detected during December, January and February, when summer temperatures were high and when routine trimming of mature canes provided the wounds needed for infection.