Deficiency in a Malawi plant

I am growing one of Ace’s Malawi, and have a potential deficiency starting. To me it looks like Mag, but I thought I’d get some input from people more experienced with Malawi than myself, I’ve seen quite a few folks here growing it lately. It is entirely at the top 25% of the plant, and only on a few leaves at this time. She is about 5 weeks into flower, and I’m growing in a SIP with mostly organic nutes, mainly top dressed with tomato tone these past few weeks and watered in with a light CalMag solution. My golden tiger is getting the same and not showing any signs. I did foiler spray them in veg, but have not since flowering. The lights are high, about 900-1200, but my co2 stays around 800 at most times. Here’s what the effected leaves look like.

Rust looks like calcium. Purple stem unless genetic is probably mag. Slight burn from too much of something. Could be a PH lockout or too high K for some reason locking out cal/mag. Check your runoff PH/PPM if possible

FWIW: I grew one a few months back. I remember it being a light feeder and skipped one or two feedings and 1/2 strength most of the time because it didn’t like much. They love light. I ran 1100ppfd no Co2. Ate it up. Those spots look more biological than a nutes issue. Bugs maybe?

tehdansauce said:

Rust looks like calcium. Purple stem unless genetic is probably mag. Slight burn from too much of something. Could be a PH lockout or too high K for some reason locking out cal/mag. Check your runoff PH/PPM if possible

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My guess is CalMag will fix it, but wanted to see if anyone growing this or other heavy sativa leaning plants had an idea. They are finicky about high nutes, so have been feeding half that of my Puck which is doing ok.

Tmik said:

FWIW: I grew one a few months back. I remember it being a light feeder and skipped one or two feedings and 1/2 strength most of the time because it didn’t like much. They love light. I ran 1100ppfd no Co2. Ate it up. Those spots look more biological than a nutes issue. Bugs maybe?

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I checked for bugs, I don’t think that’s it, and the other two plant with it have no signs, so fingers crossed it’s not. I’ve never seen bug damage that looked like a deficiency as much as this either. I have been feeding it light but may need to go lighter.

Yea, they're definitely light feeders.
Does it have yellow tips?
You have plenty of time to rectify the problem as it's probably got another couple of months to go yet.
Mine took 16.5 weeks.
I'd just give it water for a while.
Good luck mate.

Moflow said:

Yea, they're definitely light feeders.
Does it have yellow tips?
You have plenty of time to rectify the problem as it's probably got another couple of months to go yet.
Mine took 16.5 weeks.
I'd just give it water for a while.
Good luck mate.

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Yeah, the tips have a bit of burn, but I was pushing them during veg with both nutes and light. They’ve just got water for the last couple weeks, I gave them some light CalMag today to see if it helps, but nothing else. And I agree, they have a couple months at least to finish.