RESISTANCE OF NEW BELGIAN POPLAR CLONES TO BRITISH ISOLATES OF THE BACTERIAL CANKER PATHOGEN, XANTHOMONAS-POPULI

Forty-nine new poplar clones, bred in Belgium and screened there for r esistance to bacterial canker caused by Xanthomonas populi, were addit ionally screened in southern England, using British isolates of the ba cterium. Thirty-five of the test clones ranked better than the clone ' Boelare', which is already registered in the UK as an approved clone, and is regarded as having acceptable resistance. The registered clone 'Ghoy' was more susceptible, and outranked only four test clones. Prel iminary measurements of canker length and stem girdling index showed d ifferences between five bacterial isolates.