Okay.. Soooo...My 2 cents is always a little different than most people's.. Lol. With that said. I wouldnt add a thing until you figure out what the issue is.. Then, you'll have to figure out what's causing the issue, and address THAT. Adding more of whatever the deficiency looks to be, sounds good, but can easily cause more harm.. Here are 4 pics from the deficiency chart I like to use.. I posted the 4 elements that have been mentioned in this post as possible culprits. If you read them all, only one seems to have symptoms that fit/match the image you posted.
So lets say we narrow the issue down to being one of these four elements.. Now, you'll need to think about how that particular element works.. Here is the 2nd chart I use...
Whether the element with the deficiency is mobile or immobile is a vital part of fixing the issue. If its mobile, the element can be shared throughout the plant. If one leaf is deficient, the element can move from one area to another to fix deficiencies. If its immobile, that means it stays put. If one part of the plant is having a deficiency, the immobile element must be introduced to the part of the plant showing symptoms. The plant cannot move immobile elements from any part of the plant or soil. This is where foliar feeding comes into play. It applies the deficient element directly to the affected areas. And works faster than adding it to the soil. Notice that calcium is immobile, and mag is mobile... But the industry will have you believe that "cal/mag" is a thing (which it's not), when they are two completely different elements, that not only work differently, but can actually cancel each other out and create a lock out.. Can you tell that I hate the term calmag yet? Lol. And to be fair, I hate the product just as much, lol. Adding cal to the soil for a cal deficiency, doesnt do much since its not mobile. But dont tell the bottle feeders that, they wont believe you, lol.
And finally, run off... Ohhh, the dreaded run off... If you ask me.. The ph run off number doesnt mean diddly squat, lol. Its not accurate at all, and doesnt tell you anything about the soil ph. I'd get a soil ph probe.. I use the accurate 8.. For example, the ph of the water you use to create "run off" is effecting the ph of the run off.. Plus or minus? We dont know which one.. Even if you ph the water used to say 6.0.. It still tells you nothing about the soils current ph. You cpuld be raising or lowering it as you create run off..The soil ph isn't that important (as most are stable) until you have a problem like this. In your scenario, you want a legit soil ph reading.. Because it the deficiency is due to a ph swing, adding more of "whatever" isnt going to help or fix the issue.. It will make it worse.. If its ph related, the only thing that will help, is to correct the ph of thw soil.
I have a pretty good idea as to which element may be the problem child.. But I'd like to see if you can diagnose it yourself, by comparing the charts, against what it is that you're actually seeing on the plant!! You got this! And as always, we are here to help with any stumbles along the way!!
Ps.. The correct answer is NEVER cal/mag.. Lmao. It can be a cal issue.. Or.. it can be mag issue.. They are separate issues, and their deficiencies show up, and are treated, differently. But there is no such thing as a "cal/mag" issue. When you hear that term, run for the hills! Lol.
