Dieback and mortality of Chamaecyparis lawsoniana – Lawson cypress within three areas on the same site totalling 21 symptomatic or dead trees were observed. The affected trees showed similar symptoms to the first finding of Phytophthora lateralis in Scotland (reported March 2011). Five trees had fresh basal lesions and yielded a positive test for Phytophthora with a Lateral Flow Device (LFD). Positive samples were then tested further using Phytophthora-specific PCR primers which were tested on DNA extracted from bark. Resulting sequences were analysed to determine Phytophthora species.
Bark samples from 3 trees gave 100% and 99% sequence matches to Phytophthora lateralis.
Culturing from the material yielded an isolate which was confirmed as P. lateralis based on culture morphology and DNA ITS analysis. Dieback and mortality of 3 Chamaecyparis lawsoniana – Lawson cypress and 2 Chamaecyparis nootkatensis – Nootka cypress were observed.
The affected trees also showed similar symptoms to the first finding, some having fresh basal lesions yielding a positive test for Phytophthora with a Lateral Flow Device (LFD). One tree had branch dieback. Positive samples were then tested further using Phytophthora-specific PCR primers which were tested on DNA extracted from bark. Resulting sequences were analysed to determine Phytophthora species. One isolate from C. lawsoniana gave 100% and 99% sequence matches to Phytophthora lateralis.
Culturing from the material yielded an isolate which was confirmed as P. lateralis based on culture morphology and DNA analysis.
On the same site there were 2 positive identifications for Phytophthora cambivora made on Chamaecyparis lawsoniana and 1 positive identification for Phytophthora austrocedrae made on Chamaecyparis nootkatensis.
There were further findings in 2011 in Northern Ireland, then in south-west England and then in north-east England.