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Rust Spots

Discussion in 'Marijuana Plant Problems' started by deflator, Jan 25, 2010.


    deflator Active Member

    Hey all, newish grower here, legal in MI :bigjoint:

    I have a recurring problem where the leaves, starting from the middle-lower ones, start getting rust spots between the veins that multiply and then the leaves yellow and die from the tips and margins.

    This has been happening to three generations now so there is a hole in my program. Nothing I have done has helped.

    600w HPS 20/4 cycle
    65* night 77* day
    RH is low, 28-34%...it is dry as hell
    5 gal. pots, Pro-mix HP, tap water

    Ionic grow 2-1-2 and bloom 1-1-3 never at more than 50% recommended
    Green Fuse growth and bloom stims
    Tried adding lime and epsom individually without effect

    My camera is not great. This is a plant I have been vegging for awhile as a guinea pig (freebie seed). It was just topped, and tied down as an lst experiment. Only the top leaves are healthy, the lower ones keep dying on me moving upwards. I topped it aggressively because most of the leaves were dying on the main shoot, and to get 4 tops.

    I just don't get why some plants are affected in the garden and some not. The last pic is an autoflowerer grown the same way that was hardly affected by the spots at all. Could it be a mold? The guy at the hydro shop though it was blight based on my description.

    Attached Files:


    ak.fortyseven Well-Known Member

    Here are a couple links that may help you:http://www.rollitup.org/view.php?pg=faq


    Hope this helps, GL
    Yes We Canna!

    Yes We Canna! Well-Known Member

    Eesh that always a tough one.
    I always start this with a quick PH test. It seems to me like a lock up of some kind in the roots, which would mimmick a nute deficiency.
    If your PH tests normal, then you can start treeting for deficiencies. Start first with magnesium, because that's what I would do, and its easily done with some epsom salts, at 1 tablespoon per gallon of water. I would water and use a folar spray with that mixture. If that's not the case, which I doubt it would go this far (as I believe there may be a PH problem) then treat for zink, which can be found in a supplement including the trace elements Fe-Zn-Mn, which would cover any other of guesses.
    I hope this helps, let me know if you have any more questions, and keep us updated.

    deflator Active Member

    I've already done the research and tried what I could. pH after adding nutes is 6.3-6.5.

    I have tried foliar and regular applications of epsom, as well as watering with dissolved lime, and chelated Mn without effect on the leaf deformation and spotting.

    That's a nice resource ak-fourtyseven, wish I'd have seen it before I searched all those threads the hard way!

    Enigma Well-Known Member

    pH should be 6.5, .2 in either direction is acceptable.

    Add Nitrogen and Phosphorous.

    Too much Calcium and Magnesium can block Phosphorous and lock Nitrogen.

    Maintain 24/0 on veg plant until problem is resolved (damaged leaves almost stop dying and no new leaves show similar symptoms).

    Add B'Cuzz rooting solution to aid in the repair of the plant.

    Low RH exacerbates this problem.


    JohnShmith likes this.
    Yes We Canna!

    Yes We Canna! Well-Known Member

    I would stay away from adding extra N this late in the game on the one almost done... P is a great idea though for that one. Give your veggers a little boost in both for sure.
    I still suspect a PH issue, your Nute line is a decent one, and well ballanced.
    I know your checking your PH after adding nutes, now is this reading from the soil too? Sometimes it can fluctuate once it hits dirt. Give that a shot too.

    deflator Active Member

    I have tried adding Ionic boost 0-5-6 which greatly enhanced flowering on the mature plants, but did nothing to stop their defoliation.

    I have tried soil pH testers on all affected plants, though I am unsure of such a device's accuracy, and it always said 6.5-7 6 inches down. I have also tried flushing without result. The twisting of the leaves does support a pH problem hypothesis...possibly from some of my pro-mix being reused from last time?

    I am down to toxic salt buildup and Mg lockout as the only things that make any sense, but then I still cannot find a cause for either :wall:

    Or it is bad room syndrome...I found a small amount of black mold in the corner today :-(

    Enigma Well-Known Member

    How long into flowering?

    How did you transition your plant to flowering using nutrients?

    That may be natural for the plant to suck those leaves dry.


    deflator Active Member

    Last plants are done, they were autos and finished in 10 weeks from seed. Current troubled plant is 2 months old, showing only preflowers as it is on 20/4. Autos were transitioned slowly between veg and flower.
    Yes We Canna!

    Yes We Canna! Well-Known Member

    Yeah, I saw the yellowing on your babies as well, or else the natural yellowing would have been my first guess.
    To me it sounds like you're doing absolutely everything right. But, you did say you were re-using the soil? My next guess is either a lock-up from used soil, or maybe a virus of some sort being passed on via your medium.
    Is all new growth healthy and flourishing? New flower clusters looking alright?

    deflator Active Member

    Yes new growth looks outstanding, dark green and shiny, but the blotching keeps moving upward faster than it can grow away from it.
    Yes We Canna!

    Yes We Canna! Well-Known Member

    You know man, it sounds to me like there may be something else going on, outside of your control.
    You said you had found black mold in the grow area right, or close? That's dangerous, for your plants health, and yours too.
    I think there may be some mold spores hanging around the plants, causing a viral infection.
    You have two options as I see it right now, try and see if you can finish this grow out, while keeping mold and other things in control, or rip up everything now. Either option you need to toss out everything you can't clean with bleach, and scrub down everything else you can. Get new dirt, and make sure your mother isn't infected, or else it will be passed on to all your clones.
    I know that's probably not what you wanted to hear, but based on everything we've gone through, it would be the decision i'd make without hesitating.
    JohnShmith likes this.

    deflator Active Member

    Yes that was about what I was thinking too. The mold is in the drywall however, so I may need to abandon that closet all together. Or could I just bleach and paint over the moldy areas?

    My system was just autoflowerers in one room, so no mothers or any other losses except some seedlings. The big plant is a photoperiod plant in perpetual veg, something to try things on if something went wrong like this, so it could be called a mother. The rest of the autoflowerers are done, some in much the worse for wear and yield because of this problem.

    I have an old ice fishing shanty that is pretty much a canvas grow tent with the doors on the wrong sides, just the inside is matte black. Paint fumes would harm plants I'm sure.
    Yes We Canna!

    Yes We Canna! Well-Known Member

    Sometimes you can get luck and really duche the area with a strong bleach/water mixture and kill the mold spores out of the drywall. I've been both lucky, and unlucky. B it you can't kill it get the hell out of there, its definitely not worth your health.
    That shanty sounds like it could be a good thing, instead of painting it maybe getting some of that mylar wrapping paper to line it with, though once the paint is mostly dry the fumes won't affect it to much, assuming you have good ventilation in it.
    I'm so sorry this is where you're at, I'm depressed for you, large or small a viral infection is usually the last thing on our minds.

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