HELP! Weird disease/fungus? leaves yellow/brown/drying up

[firegosse]

Hi I have 3 plants currently and 1 of them is doing really great, the other 2 seem to have a problem: look at the picture to see.

If anyone knows what this could be and how to fix this please let me know. They are all autoflowers, I'm using normal potting soil with perlite and i only give them water. around 10L pots. I grow outside temp around 13-27C depending on if its day or night

The problem started happening around 1.5 weeks ago and started slowly with brown spots on the lower leaves slowly spreading to the big leaves and now it got real bad.

 

[3Berries]

Some Calcium and Magnesium should help in not adding any. More Mg than Ca at this stage.

 

[Rwise]

Whats the PH?

 

[firegosse]

Some Calcium and Magnesium should help in not adding any. More Mg than Ca at this stage.

Ok i will try this, currently i do not have any calcium or magnesium but i will try to look for some. Thanks for the advice

 

[3Berries]

I was reading yesterday on mobile nute deficiencies. These are nutes the plant needs and can't get from the soil so it takes them from the lower leaves. That is what you are seeing. So it's not calcium. Ether Potassium of Magnesium. You can directly apply Epsom salt to get the Mg. Or use it as a foliar spray. It will not fix the bad leaves but stop that from happening to others.

Calcium will show up on top.