
Fireblight is caused by a bacteria (Erwinia amylovora) which first attacks the blossoms progressing to the twigs and then the branches. Flowers turn brown and wilt; twigs shrivel and blacken, the ends often curling. In advanced cases discoloured oozing red/amber patches, form on branches. The translucent amber or reddish ooze (see image) contains masses of bacteria.
Most susceptable are : varieties of pear and apple trees (including crab apple), mountain ash, hawthorn and cotoneaster.
Treatment involves sparaying shortly after bud break, with systemic fungicide. Repeat the spray at one to two month intervals, more frequently in high disease situations.
Prune out infected branches 12 to 16 inches beyond the last visible signs of the disease on the branch. It is critical that the pruning tools be sanitized after each branch is pruned, so as to prevent spreading the disease form branch to branch.
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