Fig. 3. Comparisons of pith tissue concentrations between IHN-resistant (black bars) and IHN-susceptible (white bars) clones for each location–year. Tests of significant differences between IHN-resistant and IHN-susceptible clones within each location–year indicated above bars. *,**, and ns, significant at the 0.05 and 0.01 probability levels or not significant, respectively.