I’ve only begun using calcium the last coupe of years and was at my chemical supplier and asked for foliar calcium and he handed me a jug. I still am pretty ignorant about using it, at least on the matter of whether adding it to the tank destroys the efficacy of the Captan in the mix. I’m guessing it doesn’t though.
From my brief search on the internet it sounds like it needs to be applied earlier in the growing season, before the cells start increasing in size, to be effective, and apparently it will take a couple of years when added to the soil to show results. Foliar applications are typically calcium chloride (RotStop type products) but gypsum is usually used under the tree. So I didn’t spray as I had planned to, but I’m thinking I’ll get some gypsum down this fall and the add calcium chloride to next year’s sprays.
Bringing the pH of the soil up is inadequate. Foliar works for me if I add it to summer sprays starting in July at 2 week intervals- maybe 3 apps. I use it for Jonagold and Honeycriisp. HC ripens about mid Sept and JG mid-Oct. here.
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