Rust Spots/Burnt Leaf's/ Getting Worse

[SpliffTM]

Hey guys Spliff here, Im new to the site and this isnt the 1st post i wanted to make But i need a little advice.

Problem: Im having trouble with 1 of my DP auto Ultimate, problem started about a week ago, leafs burning/rust spots showing, it just dont seem healthy, lime ish green id say in colour. I have other autos same age in the same space and there fine.

Medium/grow method: DWC 25lt

Feed: and supplements used: GHE M/G/B 7/7/7 ml. cal-mag 10ml. PH 5.6 - 6.0 EC 0.9

water source: Tap water (Soft)

Strain/age: DP Auto Ultimate 3weeks from seed

light used: 400w mh for the 1st 2 weeks, then 600w mh for the last week or so, 24/0 cycle 16inch from tops

Climate: 24c - 27c RH 35% ish

Additional info: The damage seems to be starting at the tips and the middle of the leafs working back the way, ive already removed 2 fan leafs as the burnt to a crisp and the other 2 big leafs arent far away from doing the same.

Any help would be much appreciated

Spliff

 

[Simplicio]

There are several possibilities.

Maybe something spilled on the leaves. The new growth seems better.
EC might be a bit high for that plant. There is a large difference between what some plants can tolerate, and others can't.
Lights too close. This is what I think is most likely.
I switched from 24-0 lights to 20-4 lights a grow ago, because the plants were getting stressed from continuous light.
24-0 is simpler, and I'll eventually try that again.

If these were my plants, I'd lower ppm, raise lights, and consider 20-4 lights until the new growth looks very healthy.

 

[SpliffTM]

Hey thanks for taking time to reply,
Ive took youre advice lowered ec 0.7 raised light to 20", i also changed to 20/4 light scedule, ill try this untill the end of the week, hopefully something changes, soon

 

[Simplicio]

Hey thanks for taking time to reply,
Ive took youre advice lowered ec 0.7 raised light to 20", i also changed to 20/4 light scedule, ill try this untill the end of the week, hopefully something changes, soon

Good luck

 

[davisgirl]

I recently had a plant look just like that. Turned out to be pythium. Sucked.

What’s your water temp?

Also kind of looks like calmag. Ideal pH for calmag absorption is 6.25+.

 

[SpliffTM]

Could be an issue since i keep my ph 5.6 - 6.0, the water temps are 18c - 20c max

 

[SpliffTM]

Thought id give an update on whats happening, Ive had to remove the big fan leafs as they burnt to a crisp, not sure if its any better or worse, tbh it looks better in the pic for some reason but not to the eye.
Lights are still 20" from tops, ive lowered the ec again from .7 to .5 , still on 20/4 scedule ph 6.2

I'll give it untill end of the week if no change im gona bin it, I ordered 2 barneys auto blue cheese today
Ive added a pic of the others in the room, Auto Critical 47's on the left, with DP Auto ultimates are on the right.

 

[Waira]

did you follow up with DG's advise and check the roots? .... drifting pH can cause this as well,...

 

[SpliffTM]

Yes, roots in he left bucket are white, right bucket id say there like a tan colour (dont look to great)

 

[davisgirl]

Sometimes nutes will stain the roots. If you touch them and they feel slimy — that’s not good.

I had to restart mine. Veg time is so precious — can’t afford to lose a week like that.

Hope she magically recovers today for you. The others look beautiful.