Cause of withering of staghorn sumach (Rhus typhina L.) in selected localities in Slovakia

Health state of Rhus typhina was evaluated in 59 localities and 74 sites over the years 2001-2003 with scope (1) to identify the parasitic mycoflora of R. typhina in Slovakia and (2) to identify the occurrence of Cryphonectria parasitica, declared as an quarantine pest by the EPPO, besides the chestnut (Castanea sativa Mill.) and oak (Quercus sp.) also on R. typhina. The fungus Botryosphaeria ribis (Gross.) Dugg. (pycnidial state Dothiorella mali (Ell.) Ev) caused damage to the R. typhina. Damage to R. typhina caused by B. fibis was only recorded in 15 localities. Mean growth rate of hyphae of the fungus ranged from 25.7 to 48.3 mm after 96 hours of cultivation. The most appropriate medium for cultivation was 3% potato dextrose agar. The occurrence of the fungus Fusarium oxysporum Schlecht and mainly of quarantine fungus C. parasitica has not been recorded in the evaluated sites.