Bitter Rot is one of the few fungi that can penetrate unbroken skin of apples and pears. It can penetrate early in the season and lay dormant until conditions are right in the summer to start growing and rotting the fruit. It will rot it down and form a mummy.
https://extension.psu.edu/apple-and-pear-disease-bitter-rot/#:~:text=Bitter%20rot%20on%20apple%20and,gleosporioides%20species%20complexes.
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Really good info. Thanks for posting the link.
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Mike:
Thanks for the encouragement. It means a lot to me. My motive is primarily to assist others. I hope my efforts accomplish that goal to some small degree.
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This summer I walked around ranking my trees with respect to damage from CAR. Note that I have a LOT of red cedars, which are infected. So my experience reflects a location where the dosage of CAR spores must be quite heavy.
Here’s what I observed. This is just one guy’s observations in one season. If I grow more than one instance of a variety, I’ll give the worse performance:
Very little / no damage on Campfield, Centennial, Chestnut Crab, Dabinette, Enterprise, Franklin, Liberty, Otterson, Puget Spice, Red Byrd Bitter, Redfield, Redfree, St Edmond’s Russet, Sundance and Winesap. There was some rust damage from other forms of rust, for example on Redfield.
There was moderate damage on Ashmead’s Kernal, Black Oxford, Golden Russet, Muscadet de Dieppe, Wolf River, and Zabergau Reinette.
There was serious damage on Munson’s Sweet, Bella Rezista, Bramley’s Seedling, Harrison, Roxbury Russet, Snout’s Perfect, White Jersey.
There was severe damage on Fiesta, Jupiter, Belle de Boskoop, and Hudson’s Golden Gem.
In general, this damage did not prevent the trees from growing and producing apples. In particular, there are quite good crops on dwarf Jupiter and HGG despite the rust.
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It varies based on variety and the kind of rot. Prior damage always makes things worse, but the rot type also matters. Some varieties are very susceptible to eg bitter rot which will put a big circle on the side of the fruit. No bug or touching is needed. The truly bad rotters will rot a ton even without any damage. Some fruits are also bad rotters because they are very susceptible to damage by bugs or splits or whatever. For example earwigs and stinkbugs do minor damage to some varieties and then open up rot sites.
Here are some random apples on my counter now, they have what looks like earwig or stinkbug damage etc. The bottom two then seem to be rotting a bit around the damage. I think the bottom left got some of that on its own, it is Ashmeads Kernel which is quite prone to rot.
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Thanks