Studi sulla struttura delle popolazioni di <i>cryphonectria parasitica</i> dei castagneti del centro Sardegna finalizzati alla selezione di ceppi ipovirulenti da utilizzare nella lotta biologica

Abstract

The occurrence and diversity of vegetative compatibility (vc) types in populations of Cryphonectria parasitica, the causal agent of chestnut blight, were examined throughout five chestnut-growing areas in central Sardinia (Italy). The hypovirulent strains of the pathogen were more frequently isolated with respect to virulent ones. Four vc types were identified among the 131 isolates, obtained from 150 randomly selected cankers (30 for each area) by means of European tester isolates (EU). EU-12 and EU-2 groups were the dominant vc types, reaching a percentage of 48,9% and 46,6% respectively, followed by EU-14 (3,8%) and EU-1 (0,7%). EU-12 was found in all five populations investigated, whereas EU-2 was isolated from four populations; EU-1 and EU-14 were found each in only one population. The low diversity of the Sardinian vc types was comparable with that of other countries where the pathogen was recently introduced. The composition pattern of Sardinian vc types is very peculiar because include two dominant vc types: EU-2, usually dominant in North Italy and Western Europe, and EU-12 more frequent in Southern Italy, Balkans and Greece. In conclusion, the low diversity in vc types and the natural occurrence of superficial non-lethal cankers in all chestnut-growing areas support the possibility of successful application of biological control measures at local level in Sardinian chestnut forests