Yellow Spots - on ONE water leaf..?

This is my problem lady - in an earlier thread, she had creeping yellow crud all over. Thanks to advice from the brethren I figured out it was lack of calcium/magnesium, and a flush followed by a fresh nute mix including CalMag cured the issue. Now, she has big splashes of yellow on the top and bottom of one of her leaves, about halfway up the main stem. All the other leaves look real healthy, but I'm afraid this is a harbinger of more to come. Anybody got a suggestion on how to head off future issues? Pics attached. Thanks, y'all!

looks like thrip damage to me

thast no cal/mag issue and it not from any nut splashes. im sorry to say but it does look like pest attack. get a magnifying glass and have a look at the leafs both bottom and top and both sides of the leafs. let us know if you find anything. its the damage to the underside of the leaf that screams pest

spitsbuds said:

thast no cal/mag issue and it not from any nut splashes. im sorry to say but it does look like pest attack. get a magnifying glass and have a look at the leafs both bottom and top and both sides of the leafs. let us know if you find anything. its the damage to the underside of the leaf that screams pest

Click to expand...

I've been staring through the pocket scope til my eyeballs bleed, but no sign of anything creepy-crawly. Nothing that looks like bug shit, nothing that looks like web or foam. I shook the leaf hard over both black and white paper, and nothing came off; no moving specs. WTF?? It looks like the kind of burn you'd get from splashing something on there, but it's just that one big fan leaf. No discoloration in the veins, just those big splotches...on both sides of the leaf. It doesn't seem to be spreading to other plants, or even to other leaves on this plant. Maybe the weed fairies camped out on that leaf one night and that's just the mess they leave behind.......

My wife, who is from rural Thailand and can make anything grow (except weed), says it's "cancer" which I interpret to mean disease rather than pests. Any ideas are appreciated!