Yellow Leaf Dots Spreading Completely Over Some Leaves (It's not spider mites)

Discussion in 'Plant Problems' started by JessieDiamond, Apr 8, 2010.

  1. JessieDiamond

    JessieDiamond Registered

    Hi All,

    I'm trying to diagnose this leaf problem. It's currently affecting almost every plant in the room, some significantly (half the leaves), others totally minor. It doesn't seem to have any pattern: the edge plants (least light, least heat) have it no more or no less than the center plants.

    I know there are a lot of factors to consider in diagnosing a plant problem, but maybe someone will know what's going on -- once they see the pics and read the post. The pictures show how it progresses from tiny yellow-dot stippling, to more dot stippling, then to stipples growing in size, and finally covering the whole leaf. (It's 100% not spider mites, by the way.) The stipples generally seem to follow alongside the veins, but not exclusively.

    On the underside of the leaf, it looks like the stipple is actually a very tiny eaten area, that expands -- both in the number of them and the size. I took an extreme close-up that shows this pretty clearly.

    I can see no insects or eggs under multiple magnifications, from 2x to 100x -- and I've looked fairly often. If it's a pest, it's one that is invisible at 100x, and crawling all over my grow room.

    The room is going into the latter stages of flowering, but everything will be the same for the next grow -- so I better find out now, before I damage another crop!

    Thanks for any help!


    PS: Links to the HI-RES pictures: | Free file hosting and online storage | Free file hosting and online storage | Free file hosting and online storage

    To supplement the pics, here are the grow details:

    MAIN: 15 plants, flowered March 1st, 2010 (after 6 weeks of vegging)
    STRAINS: AK-47, White Widow, Ice, Chrystal, LA Woman (all from seed)
    GROW ROOM: 6' x 8' SCROG
    GROW METHOD: Hybrid Drip/DWC. Six self-contained totes, each its own reservoir.
    LIGHT: 2 x 1000w HPS (air-cooled vents)
    NUTES: 800-1200ppm, Lucas Method using General Hydroponics, and I don't use any other supplements (when I get more knowledgeable, I'm sure I'll start experimenting . . . ).
    TEMP: 70- to 90-degrees
    HUMIDITY: Recently upped to 50%, from 30-ish%
    PH: Mid 5's, checked regularly.
    CO2: None now. Tried for exactly one day: the room is heavily vented. Maybe next grow I'll figure a way that doesn't break the bank.

    My main diagnostic theory is HEAT STRESS, possibly compounded by low humidity. The room is really comfy now (mid-seventies, 50% humidity, well-vented), but for a good 4-weeks it was bad (mid- to upper-80's, 30% humidity). My books on growing don't mention heat stress causing dots like this.

    My minor theory is some sort of nutrient lockout. I use tap water run through a multi-stage filter, but it's not distillation -- and the tap water here is hard (about 200ppm). The thing is, I've already gone through two grows using this water and nothing like this happened.
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  2. WashougalWonder

    WashougalWonder Registered+

    I have a similar issue, and it seems I saw somewhere that it is a cal/mag def.......

    We use different water, I do not have spider mites, it is not a mold to microscopic exam.

    So, I only see in during the last 3 weeks of flower. I am trying Cal/Mag now, but I noticed it really dropped the ph of the water and I had to buffer it first. Next time I give less than the advised I think.
  3. JessieDiamond

    JessieDiamond Registered

    Tx for the input! I just wanted to add that the leaves get brittle as this stippling progresses. Still trying to pin this problem down . . . not 100% sure of the cause yet.

    I keep looking through the diagnostic pictures in my books (which are pretty extensive), and I'm not seeing a leaf that has this weird stippling. Virus? Aliens? :)
  4. Vancefish

    Vancefish Registered+

    Look here, could be (as already stated) magnesium deficiency or Ozone is also possible.

    Marijuana Plant Abuse
  5. disrupt86

    disrupt86 Registered+

    Thats not ozone or o3 problems.granted I'm looking at this. On my phone but it looks like the late stages of cal deff.what's the ppm of the water with out nutrients.
  6. Rusty Trichome

    Rusty Trichome Registered+

    Properly fill-out the troubleshooting form, and we can get a better idea of your situation. But with the info provided, looks to me like either nutrient burn or micronutrient burn.

    You mentioned not using additives...does this include foliar sprays? How about Superthrive or one of the many bulking agents? Perhaps an iron or magnesium suppliment? Looks like repeated overdosing, but would need more info to confirm or dispell. My guess is magnesium or Superthrive OD. (just a shot-in-the-dark guess)

    Then again...I'm not a hydro guy, and it might be something as simple as reservoir temps or nozzle clog. :wtf:
  7. WashougalWonder

    WashougalWonder Registered+

    Same here. Still out to lunch on this one.

    It would be nice to know what RustyT thinks it is.
  8. Jord0713

    Jord0713 Registered+

    I have the same thing going, but it only effects 1 out of 13 strains in my garden oddly. No Bugs either. For some reason the strain effected has had issues from the very get go so I haven't been too worried, just as long as it doesn't go to other plants :)
  9. Rusty Trichome

    Rusty Trichome Registered+

    It could be a limited number of things, but without knowing the exact conditions...I (or we as a community) could possibly recommend the wrong treatment or course of action, and being wrong sucks.

    Plus, guessing games cause unnecessary delays that could damage the plant(s) further.

    I know it isn't heat stress, unless the roots are being steamed, but I doubt that very much. I live with the heat every summer here in the desert where growroom temps exceed 95 daily. (with A/C running full-bore) That one I can be certain of. :thumbsup:

    My inital thought was micronute or steroid abuse. (Superthrive) But perhaps a GH nutrient OD. Hydrogen peroxide mishap? IDK...

    Without knowing what is used for ph adjusting, if anything is being sprayed on 'em, (bug sprays, tea's...) or any of the other number of things in the troubleshooting form...the list could go on a whuile.

    For faster and more accurate help, fill out the form. It only takes a couple of minutes, and could help this and future grows. There's one form for hydro, one for soil. (the link is in my signature)

    Plus...I'm not a hydro guy familiar with common hydro-specific situations, and SOMEBODY is going to need that info, lol.
  10. Actingteacher

    Actingteacher Registered

    If I were you, for future reference, I'd leave my tap water sitting out for 3 days (I'd do a week if it's really hard). How often are you feeding them nutes?
  11. WashougalWonder

    WashougalWonder Registered+

    Only pertains to flowering plants. The issue shows up at 6 weeks.

    What is your experience level? (first timer, novice, experienced...)experinced

    Your Equipment:
    .1) Type and wattage of lights. (MH, HPS, CFL's, tube fluorescents, LED's) HPS 1000 and MH 400 for last 2 weeks
    .2) Distance from tops? 12-16"
    .3) Reflector type? (cool tube set-up, bat wing, enclosed reflector, bare bulb...)Vertizontal (1000) and Sunsystems for the 400
    .4) Is there a consistent fresh air supply? 750 cfm
    .5) Do you have an exhaust fan and a circulation fan?Yes
    .6) What are the bulb wattages, kelvin ratings, and schedule? 1000-6500K, 400-2700K

    Your medium:
    .7) Specific brand and type of soil, (coco, peat based soilless...) and anything you've added to it. (vermiculite, perlite, worm castings...)FF Ocean Forest
    .8) Size of container.3 gallon
    .9) Did you use peat pucks (or similar) to root clones or germinate seedlings? no rockwool cubes

    Your nutrients and water:
    10) Source of water? (tap, bottled or filtered) What's it's ph before adjusting?RO-6.0
    11) Method of checking water ph. (ph pen, test strips, aquarium test kit...) drops into water and color match
    12) Method of adjusting water ph. (phosphoric acid, white vinegar, hydrated lime, PH Up...) Dolomite if below 6
    13) Specific brand and N-P-K ratio for each bottle. List dosages (quantity per gallon) and current feeding schedule. One feeding in flower cycle, Floral Nectar 5 drops in a quart and Ultra Snowstorm 5 drops in a does without these nutes also
    14) How often are you watering between feedings, and how much per watering?I water about every other day 2 cups or so, only when plants need it
    15) Any additives or tea's? (Superthrive, CalMag, molasses, Mother's Earth...)No
    16) Are your ph levels stable, or do they fluctuate?Stable
    17) What is your ingoing water's ph? ...your runoff ph? Have not checked runoff. 6.0 incoming
    18) Do you foliar feed? If so, with what, how often, and at what time do you spray? No

    Your growroom:
    19) Indoors or outdoors?In
    20) What size of closet, room or hut?5x10x8
    21) What are the temps and humidity levels while lights are on? ...With lights off?Not measured, but currently 75-80, unk humidity, lights off 60ish
    22) Have you seen signs of insects in the growroom?No

    Your strain:
    23) What strain are you growing? (Indica dominate or Sativa dom?)White Widow, Strawberry Cough, Haze, RMT, plus indica and sativa dominates, 8 different species
    24) From seeds or clones?Well they all started from seeds, but live as clones
    25) Is this an autoflower strain? Nope

    Ok that is about the best I can do. I don't have runoff, so no idea what the pH would be. This happens to every one of my strains at about 5-6 weeks into flower. It happens if I give the flower nutes or not.

    Where do you get straight molasses and how much in a gallon and how ofter Rusty?
    Last edited: Apr 11, 2010
  12. Rusty Trichome

    Rusty Trichome Registered+

    A couple different situations and mediums. But you might want to ask a mod to give your questions their own thread.

    Perhaps buffers in the soil are starting to fade at about 6 weeks. Kinda early for FF.

    Ummm...what do you do with the dolomite? Most companies add dolomite to potting mixes to neutralize the ph to about a 7.0ish. Not sure it's recommended to adjust water with it, or sprinkle it on the soil. In an emergency, perhaps. but I wouldn't recommend doing it full-time. It will build-up. Did this problem start when you started using the limewater?

    Do you water till runoff appears once in a while, or are you really that conservative with watering? Gotta get moisture and nutrients to the lower root zones, and an occational flush to release built-up nutrients and salts helps too. (I do monthly mini-flushes. 1 gallon of properly ph'd water to gallon of pot size.)

    6.0 is too low, and nutrients will lower the ph further. Ingoing ph for peat-based mediums is between 6.3 and 6.8 ish. Pull it out of this range and you risk lockout or using-up the soil buffers prematurely.

    I use Grandma's or Brer Rabbit unsulfered molasses at the grocery store. 1/2 tsp per gallon of properly ph'd water per week from 3 or 4 weeks into flower up until finishing flush.
    Last edited: Apr 11, 2010
  13. WashougalWonder

    WashougalWonder Registered+

    I take the dolomite if the PH is too low and crush a little bit into a very fine powder in mix in the bucket of sitting water that is kept for daily use. I only use if the PH is low. No the problem did not start with that, started watching PH closer.

    Yes sometimes I make sure and get a little run off, no dry roots, have checked.

    I could try a flush at a specific point, but my environment is so wet the pot will take forever to use it all up....Pacific Northwest on the wet side.

    Now, at this point I am trying Cal/Mag supplement, it makes the water very alkaline, 5.0 with just 2 tablespoons in 5 gallons. How do you suggest to raise the PH back up before watering over using dolomite.
  14. Rusty Trichome

    Rusty Trichome Registered+



    More perlite in the potting mix would help alleviate the moisture retention.

    Perhaps a transplant into fresh FF soil, which already has buffers in it. Or you could get some phUp...
    (5.0 ph is acidic)
  15. Rusty Trichome

    Rusty Trichome Registered+

    Anyone out there that can help the OP and his issues?
    If you get no help in here, copy-n-paste your original post to the hydro forum. :thumbsup:
  16. WashougalWonder

    WashougalWonder Registered+

    I think if we figure this out, both of us will benefit as the description including the dry crispy leaves fits to a T.

    Alkaline, acid, it is one side of 7.0 LOL :hippy::stoned:
  17. WashougalWonder

    WashougalWonder Registered+

    PH in 6.0 PH out 7.5 yesterday on one that got too dry and the water just went right through.
  18. Rusty Trichome

    Rusty Trichome Registered+

    You can't determine runoff ph using the cocor-coded test kits. The tinting of the runoff water skews results. Likely your runoff ph is fine.

    How long have they been in the same pot with the same potting soil? Old soil that has been repeatedly dried and moistened gret a tad crusty and won't absorb water likelit used to.
    If water is going right through, try a surfactant. (a surfactant lowers the surface tension of the water, allowing it to absorb easier into the medium) I use non-antibacterial dishsoap. 1/2 tsp per gallon of properly ph'd water. Should only need one application, but use no more than two waterings in a row. Make sure it's not antibacterial, or ir will kill the beneficial bacteria in the soil.

    Doubtful Jessie's problems are from the same thing. He's using a hybrid drip method, not soil. Perhaps similar synptoms, but doubtful same problem. Only way I can see it might be the same cause, is if his drip timers go too long between waterings, and you both are not getting enough moisture to the roots. But this is guesswork, as my hydro experience is zip, zero, nada. :thumbsup:
  19. WashougalWonder

    WashougalWonder Registered+

    Thanks Rusty, if I ever figure this out I will let you know what I found out. For now, I am trying a run with a little cal/mag as the only change.
  20. WashougalWonder

    WashougalWonder Registered+

    Looks like this is a more common issue than I thought
    Pictures in that one are perfect examples.
    I think maybe adding cal/mag is resolving the issue. I have to use a buffer to get my pH to 6.5......using sodium bicarbonate, doesn't take very much either.

    My current formula is 1 tsp of cal/mag in 5 gallons water, balance pH after and that is a spritz of bicarb.

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