This fast spreading and devastating disease now exists in 359 species across 59 plant families in Europe. See Xylella fastidiosa for further information. Originally spotted on olive trees in the south of Italy in October 2013, the disease has now spread to Corsica, south east France, Germany, the Balearics and Alicante.
Dr Gerard Clover, Head of RHS Plant Health, said "Xylella is very much on the move." He confirmed that once present in affected areas, the disease can't be eradicated. One possible means to prevent its spread is to create buffer zones of up to 5 kms around affected areas. Experts disagree on the effectiveness of this measure.
High risk plants include hebe, lavender, oleander, polygala, rosemary, prunus, Spanish broom and olive. Seven more new plants have been added to the list, including Calicotome spinosa (Spiny Broom), Coronilla glauca (Scorpion Vetch), Euryops chrysanthemoides (African Bush Daisy), Genista lucida (Broom), Juglans regia (Walnut), Medicago sativa (Alfalfa) and Prunus cerasus (Morello Cherry). Import, and movement within the EU, of any of these plants requires a plant passport.
If you think you have spotted Xylella, you must report it immediately.
For garden plants, contact the UK Gmt. Animal and Plant Health Agency APHA, or the Scottish Government’s Horticulture Unit. For trees, go to the Forestry Commission Tree Alert on-line disease reporting form. (But if the affected trees are horse chestnut, plane or elm trees, first check in the Symptoms are not due to other possible pests and diseases.)