Cal/mag or rust fungus

[Mooregrow]

Hi guys second grow, Northern lights auto,
I have four plants all looking healthy apart from one, I notice rust spots a few weeks ago but it was lower down on the plant and only like one or two leafs with it so I didn’t worry to much, recently noticed more and after doing some research I’m now paranoid it mite be fungus... I really really hope not. Can anyway help a brother out??

 

[Mooregrow]

As you can tell from the last pic with the larger rust spots they look very different from the newer leafs showing symptoms nearer the top

 

[Mañ'O'Green]

Looks like a problem. Let's see if we can get to the bottom of it.

Please fill in this form: (copy and paste part is below, this first one tell what specifically to include)

-Problem: (brief description)
-Medium/grow method: soil; soilless-- coco, or peat based like Promix, etc. (please provide the actual product name); DWC, NFT, etc.
-Feed and supplements used: include brand, dosage/strength, frequency of feeding and watering (alone); method-- by hand, drippers, rercirc' or drain-to-waste,... N-P-K #'s too if you can!
-Water source: RO/DI; tap- dechlorinated-?..... EC or TDS reading; pH (don't bother with this on RO/DI, do bother with TDS/EC though to confirm it's working well enough)
-Strain and age
-Climate: night and day ambient T and RH%; res' temperatures; any extremes in T/RH% exposure
- Light used: HID, LED, COB, combo of,... wattage; light cycle hours (20/4, 18/6 , etc.); distance to tops....
-Additional info: PH in the root zone. How long have the plants been affected?...How fast did symptoms appear?... Anything else you think might be relevant..

--Pictures including WHOLE PLANT PICS, and troubled leaves.. use normal light or flash as other light sources ruin color rendering, critical for diagnostics! Turn off the grow lights.

✂ - - - - - - - - - - -
(copy and paste)-->

Problem:

Medium/grow method:

Feed: and supplements used:

water source:

PH in the root zone:

Strain/age:

light used:

Climate:

Additional info:

 

[Mooregrow]

I didn’t post in the section because i never get a response, I just wanted to know via looking if anyone had experience with these symptoms