Fig. 1

Study design. Design of plant treatment and sampling. Genetically identical cuttings were positioned for 39 days in a control and an infection tent (n = 3, respectively), the latter equipped for the first 21 days with rhododendron branches covered by mature C. rhododendri spore stocks. Fans improved spore distribution and microscopic slides collected spores for concentration monitoring. One current-year shoot per plant and time point was cut, the needles detached and stored at −80 ° C for RNA and phenolic analyses. Note that on day 39 infection symptoms were clearly visible on treated cuttings and needles were separated into healthy and symptomized ones