In a recent post, I mentioned that on the Craignish peninsula, in Argyll, Japanese larch have been found to be infected with P. ramorum.
In another part of Argyll, Lawson’s Cypress trees in Balloch Castle Country Park, near Loch Lomond, are the latest casualties to the Phytophthora pathogen. In this case, Phytophthora lateralis, is the cause of the disease. Whilst “new” to Scotland, P. lateralis has been present on the Western seaboard of the USA for some time. Here it has also affected Lawson’s Cypress trees.
P. lateralis is a water-borne organism which can live and grow in the roots and lower stems of its host trees, surviving in a resting state in soil, and actively travelling in surface water. In affected trees, the foliage of the crown begins to discolour, and it wilts and withers. In small trees, this may happen over a period of weeks, and with larger trees, the process can take between 1 and 4 years.
This continual drip feed of information is starting to be a little ominous for dwarf shrubs on moorland. I will be keeping my ear to the ground.