bitter pit

I'm surprised not to find a thread about bitter pit. Are we the only ones who have it?
A long lapse in soil testing allowed our soil pH to drop to 5.6 before we realized what was happening. We started getting serious BP in Idared and Jonagold. It is a long haul to dig out of the hole we put ourselves in!
We seem to be making some progress. We applied high calcium lime (twice @ 2 T/A) and gypsum (800 lb/A) over the years and will add more. We also add Biomin Calcium or ORCA calcium to our sprays after fruit set.
Finally, in one of two our orchard sites we had virtually no BP last year; it is still bad at the other orchard.
Do others have more on this topic?

Hemlock Grove Farm
Zone 5 in New York

I too have issues with bitter pit and would love to have some insight on how to fix the issue. My soil test have come back HIGH in calcium so I just wonder if I am having issues with absorption through the roots? Or perhaps I need to apply more calcium as a foliar application? I have tried Michael's nettle tea and I suppose I just need to keep at it since this our first year using it. Perhaps I will add Biomin Calcium in the tank to give it a boost?

Thanks in advance to anyone who can help out with this.

Thank you,
Brandt

Hickory Ridge Orchard
Zone 6A in Missouri

the way I have approached this is not with more calcium as long as your soil levels AND tissue levels are adequate. A reduction in the application of any potassium in soil or tissue helps. As does the addition of foliar manganese - which somehow helps regulate the preference for calcium OVER K in the tissue. This seems to be the problem - or part of it - Potassium movement at the expense of calcium, something that manganese helps in resolving. Of course, if you are light in calcium in the leaves - calcium being very immobile - then you need more foliar calcium.

Mike Biltonen, Know Your Roots
Zone 5b in New York

It is good to see Mike's comment above, which implies the use of an amendment when a deficiency or excess shows up. This of course means testing. I almost never have a client who has had a simple soil test done (at a whopping 15 bucks), and never a tissue analysis.

There has been evidence that oversizing fruit can lead to bitterpit flare up in susceptible varieties, sadly the industry standard. Lee Kalcsits at WSU has been studying size reduction through irrigation withholding to keep the fruit smaller in cultivars like Honeycrisp.

Thanks for the good comments on this tough subject.
Certainly, testing can shed light on the situation. We use Idared as our tissue test "subject", since that variety gets bitter pit severely here (oddly, Honeycrisp has not so far). In 2018, a bad bitter pit year, it showed low Ca, K, and Mn. Soil tests tend to show low pH and calcium; high K and Mn.
We are throwing the book at it--increasing compost applications from light to moderate, putting on high calcium lime, and spraying lots of foliar Ca and a couple sprays of foliar Mn. It seemed to pay off last year at one of our two sites, where we had no bitter pit. It was still bad at the other one.
Brandt, I think nettle tea has some quickly available Ca, but much less than a full-strength Biomin Ca spray, so I would include both.
We'll see what this year brings!

Hemlock Grove Farm
Zone 5 in New York