Colin I would agree with Stephen that you don’t have enough calcium in the soil. My soil native before any amending was around 2,000 ppm Ca on AA test. After a few years of amending, it averages 3500 ppm and I have areas above 5,000 ppm. I have noticed that when we have good rainfall the plants do a pretty good job getting Ca from the soil due to all the organic matter and biology I have built up. But as soon as the heavy summer irrigation season starts, with all the high pH, high sodium, high bicarbonate well water I have, Ca goes away as does K and Na just goes crazy in the plant. My soil K averages around 350-500 ppm on the AA test, so there’s plenty there from just a “pounds” point of view. But from just a base saturation viewpoint, I average 7% sodium and 3% potassium, 12% Mg and 78% Ca. So when I start feeding K during fruit bulking because I have K deficiency, I start getting Ca deficiency too. That is much harder to fix when it crashes late season. Foliars have not been super effective but they slow the bleeding.