First report of Eutypa lata causing dieback of olive trees in Italy

In spring 2007, extensive stem and branch cankers on 4 to 5-year-old olive trees (cvs Frantoio, Leccino, Moraiolo, Nostrale di Rigali) were observed in young orchards in Umbria (central Italy) with 60 to 80% disease incidence. Ten orchards were affected, comprising 3 ha total area. Cankered areas often girdled the stem causing plant death. Symptoms were always accompanied by a dark brown discoloration under the bark extending to the xylem. Isolations from small wood pieces, removed from active cankers, onto potato dextrose agar (PDA) produced white mycelium and small black pycnidia containing conidia of Libertella blepharis ( Eutypa lata ) after 3 to 4 weeks under near-UV light. For pathogenicity testing, ten 1-year-old olive trees from each of four cultivars (Frantoio, Moraiolo , Leccino and Nostrale di Rigali) were inoculated with a 5 mm diameter mycelium disk taken from the margin of a 3-week-old colony of the fungus, by insertion, after removing the bark, into a shallow wound on the basal part of the stem of each plant. First cankers appeared 6 months after inoculation and affected 75% of the plants. One year later cankers and xylem discoloration appeared most severe especially on cvs Frantoio, Moraiolo and Leccino. This is the first report of Eutypa lata on olive in Italy. The disease occurrence in Italy was probably caused by the use of infected cuttings in nurseries and favoured by late frost injury.