Characteristics and pathogenicity of six Phytophthora isolates from pot plants

From several greenhouse plants showing foot and root rot symptomsPhytophthora isolates were gathered. Isolates fromPeperomia, Saintpaulia andSinningia were identified asP. nicotianae van Breda de Haan var.nicotianae and an isolate fromBegonia asP. cryptogea Pethybr. & Laff. Cardinal temperatures for the various isolates were determined. The specific and non-specific pathogenicity of the isolates was studied by inoculating the different crops with the different isolates, including aP. cryptogea isolate fromGerbera and aP. nicotianae var.nicotianae isolate from carnation. TheP. nicotianae var.nicotianae isolates appeared to be morphologically identical. Some of the isolates were similar in host range, but others exhibited differences in host specificity at 20°C as well as 25, 30 or 35°C. The same applies for the twoP. cryptogea isolates.