NOT since Dutch elm disease struck in the 1970s have forestry scientists in the UK been so worried. The tree disease 鈥渟udden oak death鈥� has arrived from the US and has infected four species.
SOD is caused by the fungus-like alga Phytophthora ramorum, and has been devastating California鈥檚 oaks since the mid-1990s. The alga, which thrives in rhododendron and viburnum plants, was spotted last month in southern England infecting a 100-year-old oak tree of American origin. Now it has been found in Cornwall, in the south-west, where it has been confirmed in a horse chestnut, a beech and a holm oak. All four were growing close to rhododendrons.
Sudden oak death causes a canker on the bark that weeps a dark sap, and eventually works its way right round the trunk. It doesn鈥檛 kill the tree, but stunts its growth and leaves it susceptible to other infections. 快猫短视频s from the UK鈥檚 Forestry Commission are monitoring the infestations.
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