Conidial production by <i>Botryosphaeriaceae</i> species from grapevine shoot lesions in Marlborough vineyards
Botryosphaeriaceae species are important pathogens of grapevines so the effect of environmental conditions on sporulation from naturally infected Sauvignon blanc grapevines in two Marlborough vineyards was studied. Shoot lesions characteristic of Botryosphaeriaceae infection were marked on 24 grapevines in each vineyard for observation between September 2014 and April 2015. Pycnidia on the lesions oozed conidia during or soon after rainfall on five occasions at maximum air temperatures of 8.4–19.9°C and relative humidities of 77–94.7%. Microscopic observation of the ooze showed conidia characteristic of either Neofusicoccum or Diplodia species in 67% and 50% of samples from Vineyard A and B, respectively. Sixty- nine colonies characteristic of Botryosphaeriaeae species were recovered after plating of conidial ooze and identified by DNA analysis as Diplodia mutila (39.1%), Neofusicoccum australe (30.4%), N. parvum (14.5%), N. luteum (5.8%), D. seriata (7.2%) and N. ribis (3.0%). All species have been reported previously as grapevine pathogens in New Zealand.