Survey of Oomycetes Associated with Root and Crown Rot of Almond in Spain and Pathogenicity of Phytophthora niederhauserii and Phytopythium vexans to ‘Garnem’ Rootstock

From 2018 to 2020, surveys of oomycetes associated with root and crown rot almond (Prunus dulcis) were conducted on diseased young trees in commercial orchards nurseries six provinces Spain. A total 104 oomycete isolates obtained from plant soil samples, which h identified by sequencing the internal transcribed spacer (ITS) region ribosomal DNA. Diverse species belonging genera Globisporangium, Phytophthora, Phytopythium Pythium found, vexans Phytophthora niederhauserii being most frequent. The pathogenicity these two one-year-old seedlings ‘Garnem’ (P. dulcis × P. persica) rootstock was studied. All inoculated Pp. Ph. showed severe symptoms at late stage test (defoliation, wilting dieback) several plants died. Some significantly reduced dry weight roots compared control, but this effect not observed vexans. These results provide new information about present crops Spain highlight importance carrying out frequent phytosanitary for a better knowledge potential risks posed soil-borne pathogens.