Hi! Maine had two bouts of fire blight weather during bloom, one at very beginning and second at very end.
We rarely observe symptoms in relation to the first recorded infection event during bloom. Actually, while validating the RIMpro-erwinia model (http://www.actahort.org/books/896/896_43.htm), we observed that FB was better predicted starting from the 2nd infection event. Johnson and Stockwell regularly report that Erwinia populations are too low to detect in early bloom, so it would be nice to understand a bit more what’s going on early bloom. I imagine moving bacteria from overwintering cankers to flowers as they open occurs more slowly than we think, despite temperatures favorable for FB. Originally fire blight was not a disease that required attention in Maine. That era ended about 15 years ago. We have the same story up here. Unfortunately. ;-) with only one or two strikes, but a few with considerably more. Unfortunately I think the trees are on M26. Across Maine. there seems to be much more fire blight on Paula Red than other cultivars this year. Honeycrisp and Cortland in this same block hardly affected. Timing of bloom with weather favorable for FB during Paulared bloom? be any more helpful than one? Post harvest copper make any sense? Nope. Reply: “ It should slow down with trees ceasing terminal growth. Makes no sense to spend time pruning out FB from August to October. Wait November! (After harvest) where appropriate to reduce shoot growth and thus shoot blight spread. Daily monitoring and removal of fire blight strikes starting a petal fall until end of August. Why end of August? Don’t leave fire bight cuttings in the orchard as fire blight bacterial can remain active in dried ooze for 2 years. Burn, bury, or compost the fire blight cuttings. I don’t think you need to worry about prunings. Really. Vincent Philion, agr., M.Sc. Microbiologiste/Phytopathologiste (pomiculture)
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