Evaluation of biological and agrichemical products for control of <i>Neonectria ditissima</i> conidia production

Abstract

Inoculum control is critical in containing Neonectria ditissima but no agrichemical treatments are currently available to protect picking wounds during harvesting. Inhibition of conidia production was tested using a range of chemical-based pruning paints (PP) in a field trial in 2015. Mainly Bacillus subtilis-containing, biological products (BP) were tested at the same site in 2016. The BP were also tested in a detached-lesion experiment. Spore-producing field lesions were painted with the products and spore release monitored using glass slides after each rain event. For the detached-lesion study, spore production was monitored using rain traps after weekly artificial rain events. Reduced sporulation was observed in all experiments, but not for all treatments. Some PP created a physical barrier that sealed spores in, with lesions continuing to develop below the paint. No lesion healing was observed from any product in either year, with lesion length increasing for all treatments during the experiments.