Figure 1.

Peroxidase activity in plant stems of anthracnose-susceptible (A and B) and anthracnose-resistant (D and C) watermelon (A and C) and cucumber (B and D) cultivars were monitored for 4 d in plants exposed to the four different treatments. The arrows on the graphs indicate the time at which path-1-colonized plants were exposed to the wild type. Each point represents 30 plants that were combined for the analysis. Peroxidase activity was monitored as a change in A₄₇₀ and is reported as absorbance per minute per microgram of protein. Statistical analysis (ANOVA) revealed significant differences (P < 0.05) between the treatments among time points for all varieties. Susceptible and resistant plants in treatments 1, 2, and 4 were healthy throughout the experiment and identical in appearance. Susceptible plants in treatment 3 expressed disease symptoms on d 3 and were dead on d 5. Resistant plants did not show disease symptoms with any of the treatments.