Validation of New Zealand Psa forecasting model in Emilia Romagna Region, Italy

Abstract

A forecasting model to predict the kiwifruit bacterial canker infections was developed in New Zealand. In 2012, we started the validation of such forecasting in the kiwifruit growing areas of Emilia-Romagna Region. Validation was carried over 2012-2014, exposing micro-propagated potted kiwi plantlets under untreated infected plants from march until November and check them for symptom occurrence, along with pathogen isolation on selective growing media and PCR determination on isolated bacterial colony. Over the years 2012-2014, symptoms on plantlets were always observed from March to the first week of June. In the same period, disease symptoms occurred in the untreated kiwifruit adult vines, confirming what observed in potted trap plants. However diagnostic analysis showed that bacteria can be detected in potted trap plants throughout the year (particularly in 2013 and 2014), except some sporadic week during summer even without a rain event. Validation experiment using trap plants allowed to validate the forecasting model during springtime (from March to June) showing a robust correspondence between the model prediction and the symptom occurrence as well as the bacterial inoculum contaminating the trap plants during the growing season.