Pathogenicity of threePhytophthoraspp. causing late seedling rot ofQuercus ilexssp.ballota

Abstract

SummaryWithin a research project on quality of plants for forestation of agricultural lands, we studied the aetiology of a late seedling rot affecting holm oak (Quercus ilexssp.ballota) in two forest nurseries in southern Spain. Major disease symptoms were foliage wilting and necrosis of feeder roots.Phytophthora cinnamomi,Phytophthora cryptogeaandPhytophthora drechsleriwere isolated from necrotic roots of holm oaks. Selected isolates of the threePhytophthoraspecies were pathogenic toQuercus ilexssp.ballotaandQuercus suberseedlings in artificial inoculations. Soil flooding conditions were essential for infection and root rot development. There was no host specificity among the species, the isolates ofP. cinnamomibeing the most virulent in all inoculated plants. In these inoculations,Q. ilexssp.ballotaplants were more susceptible than those ofQ. suber. This work is the first report ofP. cinnamomi,P. drechsleriandP. cryptogeaaffectingQ. ilexssp.ballotain forest nurseries.