PREDICTION OF SYMPTOMS OCCURRENCE OF FIRE BLIGHT (ERWINIA AMYLOVORA) BY THE MARYBLYT^TM PROGRAM IN RÍO NEGRO, ARGENTINA

Erwinia amylovora is the causal agent of fire blight, a quarantine disease for Argentina, which causes great economic losses in pome fruit in Europe and North America. Due to its high power of multiplication and form of dispersion, the diversity of susceptible cultivars and rootstocks and the ability to use ornamental Rosaceae as reservoir hosts, actions are needed to adopt measures in order to prevent it entering Argentina. The aim of this study was to evaluate events of potential infection of E. amylovora using the Maryblyt^™ forecasting program in the Alto Valle de Río Negro, the most important production area of pears in Argentina. Historical records database from 1970 to 2009 for ‘Bartlett’ was taken from a weather station located at INTA Alto Valle Research Station (39°01’00”S; 67°40’00”W). Due to the model assuming the presence of inoculum in the environment, and that this is a bacteria free zone, states “infection” and “high” were only considered to the development stage “blossom blight symptoms”. The results indicated that there was high risk of infection in 16 of the tested seasons. It was observed further that these events occurred in eight of the last ten years. These results could be associated with climate changes. The Alto Valle area is historically characterized by unsuitable weather conditions for the development of pathogens in particular by its low relative humidity and low rainfall. However, this study would demonstrate that these conditions are sufficient for the initiation of an infection period by E. amylovora, although these infections cannot progress due to the above described climatic feature. As mentioned, this pathogen is not currently present in our country. The introduction of new plant materials and the installation of pome tree fruit in marginal areas must be reconsidered to avoid the introduction of this pathogen.