After assessment of symptoms, field vines were vegetatively propagated for further experiments. First, V. cinerea B9 vines were propagated in 2010 as described previously (Barba et al. 2015): briefly, dormant cuttings were taken from the vineyard, stored at 4 °C and potted in a 3:1 mixture of perlite: soil with bottom heat at 26 °C until sufficient rooting took place. Vines were then grown in a greenhouse under a 16 h photoperiod at 27–30 °C, pruned and stored at 4 °C for dormancy. In 2011, potted vines were grown in a greenhouse as described above and pruned to assure uniform vegetative growth when needed. Secondly, dormant cuttings from resistant and susceptible plants were sent to California to confirm phenotypes under controlled conditions (i.e., symptoms were due to D. ampelina alone). From cross ‘Chardonnay’ × V. cinerea B9, four resistant progenies (454064, 455035, 454053, 454058) and six susceptible progenies (454066, 454071, 455072, 455082, 454045, 454077) were propagated. Twelve replicates per genotype were established in the greenhouse at the University of California Experiment Station in Davis as a source of green cuttings for the following experiments. Dormant cuttings taken from the New York vineyard were surface sterilized in 1% sodium hypochlorite for 15 min, soaked in water overnight and then callused in boxes filled with perlite and vermiculite (1:1, vol/vol) for 21 days at 30 °C and 85% relative humidity. After callusing, cuttings were planted in sleeves in a 1:1 mixture of perlite and vermiculite and then returned to 30 °C at 85% relative humidity for 14 days to further encourage callusing. Plants were afterward placed under intermittent water mist (5 s every 2 min during daylight) at 28 °C for 7 days in the greenhouse, at which point leaves emerged and plants were then transferred to the greenhouse and potted in UC mix (Baker 1957). After 5 months [natural sunlight photoperiod, 25 ± 1 °C (day) and 18 ± 3 °C (night)], there was sufficient shoot growth for propagation of plants from green cuttings for inoculation experiments.