Infected plant tissues are an important primary inoculum sources for plant bacterial diseases. This study investigated the survival of Xanthomonas campestris pv. viticola (Xcv), the agent of bacterial canker of grapevine in infected tissues on soil surface and during composting process of pruning residues. Grapevine plants cv. Festival were inoculated with a mutant resistant to rifampicin Xcv2Rif and maintained under greenhouse conditions until presenting high disease severity. In the first experiment, fragmented shoots and entire leaves from these plants, were placed into mesh bags and located on the surface of microplots. In the second experiment fragmented shoots and leaves were also placed into mesh bags and located inside composting piles of grapevine pruning residues. The survival of Xcv2Rif in infected tissue was monitored at 8 and 10 days intervals from 1 and 2 experiment setting, respectively. In the experiment 1 tissue decomposition was also evaluated and in the experiment 2, pile temperature curves, phenolyc content, and antagonism against Xcv2Rif were analyzed. The pathogen survived in high populations for at least 80 days in grapevine-infected tissues on soil surface. The composting process eliminated Xcv2Rif from crop residues in 10 days due to high temperatures, liberation of phenolyc compounds and microbial antagonism. In conclusion, Xcv survives in grapevine infected tissues on soil surface at least until 80 days but is eradicated by composting in 10 days.
Bacterial canker of grapevine; crop residues; epidemiology; Xanthomonas campestris pv. viticola; erradication
