Return of the elm

摘要

One of the first things I learnt as a horticulture student at RHS Garden Wisley were the Latin names Scolytus scolytus and Ceratocystis ulmi. These were, respectively, the elm bark beetle and the fungus it spreads (since renamed to Ophiostoma novo-ulmi). The fungus is better known as Dutch elm disease (DED), scourge of Ulmus, and the cause of more than 20 million elm deaths since the late 1960s in the UK alone. All elms can be affected to differing degrees, as can related Zelkova species, although these are generally less severe, English elms (forms of Ulmus procera, Ulmus glabra and Ulmus carpinifolia) are among the more susceptible.