Bitter Rot, Black and White Rot on Apples

Could one of you apple gurus explain the difference in these diseases
and how to treat them. Thanks


Are there no apple gurus on the forum?


I struggle with prevention and identification of all the summer rots you identified. For sure, I am no expert! Last year, I got nailed by Bitter Rot which I originally thought was White Rot. The good news is that Captan is pretty effective against all the summer rot diseases.

The link below is some of the best information I have found and I use it a lot. White rot is listed as “bot” rot:

If you want to spend $100 on a good disease textbook for apples and pears check out this one:

1 Like

Thanks Rick. I’ve seen bitter rot before, but since I grow very few apples,
have never paid much attention to it. But this year I expect a decent harvest
from the 4 trees I have, and wanted to be prepared, in case I see it again.
It’s a good thing Captan is cheap, but I doubt that I’ll spray, unless it gets
out of hand. I’m pretty good on orchard sanitation. Thanks again.

1 Like

I had over 50 big fat gold rush apples this year. Unfortunately I’m down to a half dozen due to summer rot. I guess I better get on a treatment program next year. I saw some rot last year which was much more prevalent in non bagged apples. I should have bagged this year but decided to try the footies vs nonbagged. The cooties made no difference in bug damage because I have none. Im extremely careful with sanitation. But it’s not enough in my yard. Grrrrrrr.

1 Like

I could have written your same post-gold rush, lots of apples, excellent sanitation, 90% lost to rots. I’m in a very similar climate to yours, too, though this has been an exceptionally wet summer. I think mine is mostly bitter rot and maybe glomerella, but I’m not experienced enough to know for sure.

What’s your treatment plan for next year? Captan? I sprayed two sprays of myclobutinol early season for cedar apple rust control, which worked very well. I’ve read a bunch of stuff about Merivon being very effective but the price I’ve found means I won’t be buying it.

I learned the hard way that summer rots can be terrible in a hot humid climate when it rains a lot. Unfortunately, no sure fire control exists. Most commercial apple growers had big problems with Bitter Rot last year in NC even with aggressive spray programs where “cocktails” of multiple fungicides were sprayed often. Merivon + Captan helps but once the rot hits, its too late. The recommendation for my state in a wet year is to spray fungicide every 5-7 days. I’m not willing to do that which is one very good reason not to grow apples in a hot humid climate. I have less rot on the varieties that ripen early.

Thanks for the input. My plan is to do zip lock bags. If that does not work, I’m sticking with pears. There’s no way I will motivate to spray as much as necessary for control. My neighbor’s pears have almost no rot. I think it is pineapple pear. Between the fireblight and rots, I’m having very little success with apples. I just chopped down my nice king David tree due to stealth fb that I missed last year that moved down into the trunk.