Fig. 2

Summary of powdery mildew susceptibility of the four genotypic classes within the F1 population. Susceptibility was assessed on leaves and canes of field-grown vines in 2013 using natural powdery mildew inoculations, as well as artificial inoculations in the field during 2014 of greenhouse plants and detached leaves in vitro. A 6-point rating scale, 0 (no visible symptoms) to 5 (powdery mildew covers all tissue) was used to determine powdery mildew susceptibility for field evaluations in 2013 and 2014. Powdery mildew susceptibility was rated using a 5-point scale, 0 (no symptoms) to 4 (powdery mildew covers majority of the leaves) in the greenhouse and in vitro assays. Significant differences detected with Tukey’s test are indicated with different letters. The letter ‘n’ denotes the number of genotypes used for analysis in each of the disease evaluation methods. The E. necator biomass was measured by qPCR, plotted infection coefficients correspond to natural logarithm-transformed 2^-ΔCT values. The higher values indicate less biomass accumulation