La xylella fastidiosa, il batterio che dal 2013 ha arrecato danni gravissimi agli ulivi pugliesi e contro il quale non c'è rimedio, è stato segnalato anche in Svizzera. Le piante infette scovate sono state quattro, tre delle quali in un centro di Dürnten (ZH), fra i maggiori vivai del paese. La segnalazione di casi sospetti è giunta nell'agosto del 2015, ma è venuta alla luce solo oggi grazie a un articolo del TagesAnzeiger. Il rimedio è stato radicale: abbattute e bruciate le piante infette e quelle vicine, anche se sane, mentre in un raggio più ampio si è proceduto ad un accurato esame. L'intervento sembra essere riuscito, perché controlli successivi non hanno più evidenziato la presenza del batterio, così come i 9'954 effettuati lo scorso anno dall'Ufficio federale dell'agricoltura sulle importazioni.
La xylella è diffusa soprattutto in America latina e le piante di Dürnten arrivavano da lì via l'Olanda. Anche in Europa, però, è sempre più presente: in Corsica, nel sud della Francia e in Sassonia, con il medesimo ceppo che annualmente causa perdite per milioni alle vigne californiane.
Le specie potenzialmente minacciate sono 300, dalle rose agli alberi da frutta. Le piante malate seccano inesorabilmente. La minaccia viene anche dal turismo: chi rientra dalle vacanze con un souvenir vegetale rischia di scatenare il contagio.
pon
RG 18.30 del 09.08.2016 La corrispondenza di Marzio Minoli
RSI Svizzera 09.08.2016, 20:30
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