FIGURE 1.

Mean B. lactucae conidia per plant was lower in UV-B (white bar)-pre-treated plants than control (gray bar) plants of multiple lettuce (L. sativa) cultivars (n = 13–16). Pedrola was completely resistant to B. lactucae infection as denoted by the letter R. Lettuce plants were treated with photosynthetically active radiation (PAR) + 0.5 μmol m^{– 2} s^{– 1} UV-B or PAR only (control) for 3 days and then inoculated with 10⁵ conidia mL^{– 1} of B. lactucae. At 12 days post-inoculation, plants were washed and the resulting conidia suspension counted. Error bars indicate 1 SE. Asterisks indicate significant differences between control and UV-B plants according to a t-test within each cultivar where **p < 0.005, ***p < 0.0005, ****p < 0.00005.