Training apples for high density and avoiding the spread of fire blight
Avoid high density training on apple varieties susceptible to fire blight during infection periods, as this can encourage the spread of bacteria.
In my previous Michigan State University Extension article “Training apples for high density systems,” I gave some tips on training branches in high density apple plantings. I managed to forget to add a paragraph in that article regarding fire blight. If training susceptible and highly susceptible varieties to fire blight such as Honeycrisp, Gala, etc., be sure monitor fire blight activity in the young orchard. I have made the mistake years ago and trained trees during this period and managed to spread the disease right down the row!
The period for flower bud initiation for apples in the northern United States may coincide with fire blight activity. Be sure to avoid training on these susceptible varieties when there are high fire blight infection periods and warm, humid conditions which can encourage the spread the bacteria. On these varieties, try to train when you have dry conditions and low fire blight infection periods or no sign of the bacteria.
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