Could these Dark Brow Spots be Leaf Septoria?

[IceR]

Hi,

I am on my 3rd grow in the 7th week and since two days dark brown spots have appeared on one of my plants (4 in total). it started with one leaf and is now on 5/10 leaves on that one plant. i am wondering if it could be Leaf Septoria as some of the symptoms seem to match but so does phottasium defficiency

a bit about my setup

• Growtent 0.8m x 0.8m with 128 watt LED ate 30 cm distance
• 4 plants in soil (11 L containers)
• Amnesia Haze Autoflower
• germinated on 13-10-2020 on light: 18/6
• started using canna terra vega 25ml/10LT and last week shifted to canna terra flores 25ml/10lt (both 50% of recomended by manufacturer, because of them being auto flowers).
• Temperature has been between 19 - 24º C and 50/60% humidity
• Airvent on 24/24 + ventilator

Last watering of this plant 25-11-2020
Feeding water: ph 5.8 ppm 435
runofff water:ph 6.25 ppm 695

As i understood that in case of Leaf Septoria i need to remove affected leaves asap i need to diagnose this quickly.

Any help greatly appreciated.

 

[Beachwalker]

Your pH is too low for soil and you're locking out probably phosphorus; you need to use pH 6.5 for soil

Edit: hold on I just saw this!?
Brown circle with black ring

I believe the majority of the leaf damage is from improper pH lockout however it's possible the brown spots with black ring could be a leaf septoria, not saying it is saying it's possible

if it is septoria I recommend liquid copper fungicide I had great results with it haven't had septoria come back in about 4 years

Recommend before you do anything you get other opinions because if I'm honest I'm not positive, I know it's one of the two things I've mentioned, but it could be both ?

 

[IceR]

Your pH is too low for soil and you're locking out probably phosphorus; you need to use pH 6.5 for soil

Edit: hold on I just saw this!?
Brown circle with black ring
View attachment 1062910

I believe the majority of the leaf damage is from improper pH lockout however it's possible the brown spots with black ring could be a leaf septoria, not saying it is saying it's possible

if it is septoria I recommend liquid copper fungicide I had great results with it haven't had septoria come back in about 4 years

Recommend before you do anything you get other opinions because if I'm honest I'm not positive, I know it's one of the two things I've mentioned, but it could be both ?

Hi Beachwalker, thanks for the quick reply :-)

i´ll wait for some other opinions but i am bit worried as it went from 1 to 2 to 7 leaves in 2 days. And with this speed, if it is septoria, looks like it could affect the whole plant.

Also if the problem was ph wouldnt it have started immediately after the watering?

 

[Beachwalker]

bump

 

[IceR]

bump

What do you mean by "bump"?

so watered yesterday with ph 6.5 so hope the spreading will now stop.

As the affected plant is also in contact with some of the other plants but it doesnt seem to spread to any of them leads me too think its not septoria. Or am i thinking wrong?

 

[Beachwalker]

What do you mean by "bump"?

so watered yesterday with ph 6.5 so hope the spreading will now stop.

As the affected plant is also in contact with some of the other plants but it doesnt seem to spread to any of them leads me too think its not septoria. Or am i thinking wrong?

I don't think it's septoria; I bumped it because I was trying to get more input

 

[IceR]

@Beachwalker,

As the spreading of the symptoms have halted completely after i watered 5 days ago with ph 6.5 i am pretty sure you were right and the ph was the problem, no septoria :-)

Thanks again for your help

 

[Beachwalker]

@Beachwalker,

As the spreading of the symptoms have halted completely after i watered 5 days ago with ph 6.5 i am pretty sure you were right and the ph was the problem, no septoria :-)

Thanks again for your help

You're very welcome, glad I could help!