<i>Neonectria ditissima</i> spore release and availability in New Zealand apple orchards
Conidia and ascospore release of Neonectria ditissima, the causal agent of European canker, was investigated using rainwater traps and VaselineÂ®-coated glass slides in the Tasman region, New Zealand. Trapping of spores was carried out from May 2013 to June 2015 in three separate apple orchard blocks planted with â€˜Scifreshâ€™/Jazzâ„¢, â€˜Royal Galaâ€™ and â€˜Braeburnâ€™, respectively. Conidia and ascospores were both produced at any time of the year when rainfall occurred. The numbers of both conidia and ascospores trapped peaked in Aprilâ€“May, but were produced throughout the year. There was a trend for lower spore numbers with increasing number of non-rainy days prior to rainy event 2mm, while more spores were trapped under frequent rainfall conditions. There was a significant correlation between mean conidia trapped and total monthly rainfall in all three orchards, but ascospore numbers were significantly correlated with rainfall on glass slides only in the â€˜Braeburnâ€™ orchard.