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Seasonal Dynamics of Taphrina deformans Inoculum in Peach Orchards

The dynamics of the inoculum of Taphrina deformans were studied during a 4-year period by (i) inspecting curled leaves for the presence of asci, (ii) placing deposition spore samplers within the tree canopies, and (iii) exposing potted peach plants (trap plants). These three approaches produced consistent results. Four main periods characterized the dynamics of the inoculum: the first period coincides with the parasitic stage of the pathogen's life cycle and the other periods with the saprophytic stage. Mid- to late spring (first period) was characterized by the presence of asci on infected leaves which produced and ejected large quantities of ascospores in 96% of the samplings. Rainfall was not necessary for ascospore dispersal, which was favored by air temperature <20°C and relative humidity ≥80% or wetness duration >8 h. In summer and autumn (second period), blastospores were trapped in 54 and 24% of samplings, respectively, with low spore numbers. In the winter (third period), blasto-spores were trapped in the lowest numbers and in only 6% of samplings. In late winter to early spring (fourth period), blastospores were found in 56% of samples, with increasing numbers. Rainfall significantly influenced blastospore dispersal and temperature was correlated with the seasonality found during the saprophytic stage.