Brown spots on leaves: fungus/Septoria?

[Diegovvvv]

Hi everyone. Does anyone knows what these brown spots are. Haven't seen something like that before.

This is a sativa.on its 5th week.

I did a quick search on G and some photos talking about fungus/septoria look pretty close to my plant. These spots are.on the top leaves.

Soil: plagron batmix
Nutes: plagron sugar royal 1ml/l
Light: LED 350w full spectrum

 

[Herby Paisley]

It could be the beginning of a potassium deficiency...

 

[Emilya Green]

top leaves means it is a non mobile element, confirming calcium to be the culprit. A bit of calmag could make this stop progressing.

 

[Diegovvvv]

top leaves means it is a non mobile element, confirming calcium to be the culprit. A bit of calmag could make this stop progressing.

Thanks @Emilya any idea about a homemade/pharmacy nutrient? Growshops in my city are closed.

Thanks in advance for your input.

 

[Emilya Green]

Emmie's DIY CalMagPhos+ From Eggshells

This is an awesome product to use during the changeover period from growing to flowering/fruiting on all of your plants. For most of us, by using molasses we are able to get the magnesium that our plants need, but for our calcium needs, most of us have to fall back on a commercial product, and...

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