Effect of burning and high temperature on survival of Xanthomonas translucens pv. pistaciae in infected pistachio branches and twigs

This paper reports the efficacy of burning and heat-treating pistachio branches and twigs as a means of disposing of prunings from trees infected with Xanthomonas translucens pv. pistaciae (Xtp). Burning of pistachio wood, naturally infected with Xtp, was conducted twice under field conditions. Viable Xtp was detected in some non-burned wood, but not in charcoal, ash or partially burned wood. Controlled laboratory experiments were conducted with pure cultures of Xtp and naturally and artificially infected pistachio wood. In liquid culture, 65°C was lethal to Xtp, whereas survival at 60°C or less varied with culture medium and duration of exposure. Xtp survived in infected wood exposed to 40–55°C for at least 60 min but was killed by exposure to 60°C for 15 min or more. Overall, the results of burning and heat treatment were consistent, and confirmed that burning was a reliable eradication technique to dispose of infected wood, such as prunings, providing the pathogen was exposed to a temperature of 60°C or greater for at least 15 min.