A subset of 12 cane-resistant (scores 0 or 1) and 12 cane-susceptible (score 2 or 3) progeny from ‘Chardonnay’ × V. cinerea B9 were selected to maximize the number of progeny with recombination events around the Rda1 resistance locus. On August 29, 2013, three shoots on each field-grown vine was spray inoculated using a Preval handheld paint sprayer (Preval, IL, USA) immediately before sunset and enclosed in a moistened plastic bag to maintain surface wetness. The next morning (at 14 hpi), inoculated stem internode between the second and third unfurled leaf was collected, immediately stored in liquid nitrogen and transferred to the laboratory for RNA extraction.