Fire Blight Risk Assessment in Girona Region(Catalonia): Comparison of Maryblyt and Cougarblight Models

Abstract

Fire blight is a serious disease of apple and pear in some areas of Catalonia (Northeastern Spain). However, fire blight has only been detected in a few trees of two orchards in Girona region in the last 10 years. The first detection took place in 2007 on pear and the second one occurred in 2013 on apple. All the trees in the affected orchards were eradicated according to the legal measures. Fire blight can quickly become an epidemic in Catalonia, for this reason an intensive surveillance has been done in the last years through rigorous disease monitoring. In order to have a better guidance for inspection, two fire blight predictive models were used: Maryblyt and CougarBlight. The fire blight risk was established during 2013, 2014, 2015 and 2016 on pear (cv. Conference) and apple (cvs Fuji, Gala, Golden and Pink Lady©) using meteorological and phenological data of three representative locations. A detailed analysis was also performed in an apple orchard placed near to the location where the last outbreak had been detected in 2013. Results showed that CougarBlight is more appropriate than Maryblyt when the disease is not present in the area using the scenario 1 (no fire blight in neighborhood orchard last year); according to CougarBlight the overall fire blight risk in Girona was low or moderate. When forecasting models are used to guide the inspections in orchards, Maryblyt or CougarBlight with scenario 3 (fire blight is now active in the neighborhood orchards) are useful