HELP! Can anyone identity if this is cannabis septoria?

[Namelessbob]

GSC auto in 10 litre air pot of coco coir, using the canna range of nutes under one Mars Hydro TS1000.

Week 4 into the grow and the past week or so I’ve noticed a change to the fan leafs. It’s started from the lower leafs and has moved onto the further ones up. I’ve searched the internet trying to diagnose what is happening here. I’m sure my nute levels are ok and the water ph is 5.9-6.1, typically where it’s liked it in previous grows. The most fitting conclusion I’ve came to is that it could be cannabis septoria. I have used the medium that it’s growing in before, so this may be the origin of the problem. If anyone that knows better and can help, I’d be very appreciative, thanks.

[azorahai]

It could also be a symptom of calcium deficiency, which doesn't necessarily mean there's not enough calcium in the medium, though that's what you should check first. I'm having a lot of problems with calcium deficiency right now for a bunch of reasons, but I've noticed that the leaves receiving the most amount of light are also the most affected. I've increased the amount of calcium in my nutrient solution, and also increased air circulation in the grow space to increase transpiration and consequently increase nutrient absorption from the medium (decreasing your RH would also help). Calcium can also get locked out if your pH is too acidic (below 6.2, i.e. the plant will absorb less and less as it gets more acidic than this), or if there's too much potassium, phosphorus, and several micronutrients in the medium.
Go over these variables and see if anything could be interfering with its absorption before moving on to other possible causes.

[BaccaRacca]

That was my initial reaction, as well. GWE Link seems similar: https://www.growweedeasy.com/cannabi...ium-deficiency

[gbauto]

I typically see Septoria on my outdoor grows during the summer.
If that spotting is primarily on older growth, I'd look for a reason why you're not uptaking Calcium.

[Namelessbob]

Thanks guys for your response,

I’ve just started a new bottle of cal/mag so I’ll chuck it out and get a new one and use that instead. Thanks for your help, I’ll keep you posted on results.

[Rwise]

I dont do coco, but did you pre-treat it?
What is the PH of the run off waters? The first thing to look at when you have a lockout or deficiencies is PH.

[9fingerleafs]

Rehousing coco can result in root rot. You need trichoderma harzianum, it’s a beneficial fungi, one of the ingredients of mycorrhizae. It’s cheap and you drench the pots and that’s it.

About the spots. Most likely you have a calcium Hungry plant. I would just get some calmag and add to you regime at a low dose.