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A forecasting system for bacterial spot disease of stone fruits caused by Xanthomonas arboricola pv. pruni

Isidre Llorente: University of Girona

<div>Bacterial spot disease of stone fruits, caused by <em><u>Xanthomonas arboricola</u></em> pv. <em>pruni</em>, is of high economic importance in the major stone-fruit-producing areas worldwide. As no effective chemical control is available, quarantine measures are needed to avoid pathogen introduction and dissemination. In affected areas, control is mainly based on preventative copper spray applications and antibiotics (where they are registered). Appropriate and rational timing of copper would increase the efficacy of disease control. The study was aimed at developing a mechanistic forecasting system for this disease based on three components: i) epiphytic inoculum potential, ii) weather conditions conducive to infections, and iii) disease symptom appearance. The effects of environmental parameters and inoculum populations on different steps of the disease cycle were quantified and modeled. Models for predicting bacterial growth as a function of temperature, infection risk based on wetness period duration and temperature, and symptom development based on cumulative degree day were developed. Inoculum dose threshold and infection risk threshold were determined. The results obtained, performed under controlled environment conditions, contribute with new knowledge on the epidemiology of the bacterial spot disease and offer new possibilities in the disease management. This research was supported by grants AGL2013-41405-R (Spain) and EU FP7 number 613678 (DROPSA).</div>