Disease development, quality, and bittering acids content of hop cones when inoculated with Podosphaera macularis in varying developmental stagesa.

a Cones were inoculated with a suspension of 105P. macularis conidia per ml on the dates indicated and measurements were taken at harvest during mid August to early September, depending on year. Treatments within a column and the same year followed by different letters are significantly different based upon a mixed model analysis with an F-protected least significant difference (α = 0.05).b Disease severity was assessed on a 0 to 8 ordinal scale, where 8 is the greatest possible disease severity as described in the text. Cone color was assessed on a 1 to 10 ordinal scale (Fig. 1). Ordinal data was analyzed using a nonparametric analysis and ANOVA-type statistic. Relative effect (RE) ranges from 0 to 1 and provides a measure of treatment effects for a given experiment [26]. Significant differences in relative effect are inferred by lack of overlap of the 95% confidence intervals, which are presented parenthetically.c Bittering acids and Hop Storage Index (HSI) were determined by the American Society of Brewing Chemists spectrophotometric method [24]. Hop Storage Index is a measure of relative loss of bittering acids. Increasing values indicate an increase in degradation of bittering acids.Disease development, quality, and bittering acids content of hop cones when inoculated with Podosphaera macularis in varying developmental stagesa.