Removal Of Off-Season Flowers In Order To Avoid E-Amylovora Infection In Pears

During the autumn season, the climatic conditions in Israel are often conducive to outbreak of the fire-blight epidemics. The combination of optimal temperature, high relative humidity and rains, and the prevalence of E, amylovora bacteria, threaten susceptible hosts. Although pear trees are facing the dormancy stage at that time, flowering is not uncommon. These flowers are very susceptible to E. amylovora infections.Prevention of off-season bloom may limit or even preclude fire-blight outbreaks during the autumn season. This can be achieved by implementing two different strategies: (a) Prevention of off-season flowers by implementation of integrated horticultural growth management. The key factor is to prevent any stress condition, e.g., water stress, summer pruning, etc. (b) Removal of off-season flowers by chemical means. Spraying of a chemical is applicable only if it does not affect the next year's crop.This research report summarizes 3 years of field experiments, where 10 different chemicals were tested. Only two of the chemicals - "Ethylen" 0.1% or 0.2% (480 gr/l Ethephon, SL) and "Wilthin" 1% or 2% (Amads= 1-aminomethanamide dihydrogen tetraoxosulfate) showed promising results. Flowers were defoliated either 14 (Ethylen) or 2 (Wilthin) days after treatment (respectively), without affecting the crop in the following years. Fire blight symptoms were not observed on any of the treated flowers.