Studies of infection withxanthomonas campestris pv.vesicatoria,causal agent of bacterial scab of pepper in Israel

Xanthomonas campestris pv. vesicatoria, the causal agent of bacterial scab of pepper, was isolated in several regions in Israel. When artificial inoculation was practiced, pathogen growth was enhanced by high temperatures (30-36°C), and an inoculum concentration of 10^p6 colony-forming units (CFU) per ml was optimal for symptoms to develop on plants. Pre-inoculation treatments such as wounding the leaves by rubbing them with carborundum powder or spraying them with diluted wax solvents, markedly increased disease severity, but were not essential. Pre-inoculation conditioning at two different relative humidity levels (R.H. = 100% or R.H. < 40%) did not affect disease severity. Young leaves were more severely affected following infection than older leaves. Disease severity was similar with several isolates ofX. campestris pv. vesicatoria.