Yellow leaves/brown spots during flowering

Discussion in 'Plant Problems' started by Ziggilus, Jul 22, 2010.

  1. Ziggilus

    Ziggilus Registered

    My plant is about halfway through the 4th week of flowering. Over the past week or two a problem has developed and I am not sure of the cause. It started with a few small brown spots (about the size of a pin hole) on the middle to upper leaves on the main stem. As these spots accumulated the lower leaves began to yellow between the veins (with the veins remaining green) before turning completely yellow and eventually dying (some leaves accumulated large masses of the brown dots in the middle of the leaflets, while others simply died with only a few spots). The yellowing has now progressed about 3/4 of the way up the main stem, and is beginning to work its way up the side branches. The spots are now beginning to appear on the upper leaves of the side branches as well, whereas before they were only on the main stem.

    My upper leaves are curled down on the sides (like an upside-down canoe) and some have a curled claw shape. This made me think I had an over fertilization problem, but a flush last week produced no results. I also tried epsom salts at 1/2 tsp/gal at the beginning of this week, thinking it may be a magnesium deficiency (I use distilled water) but this also has proven unsuccessful.

    Brown spots:

    Solid yellow leaf with brown splotches:

    Yellowing between veins:

    Leaf canoeing/curling:

    Troubleshooting form:

    What is your experience level? first timer

    Your Equipment:
    .1) Type and wattage of lights. 23W CFLs x 6
    .2) Distance from tops? approx. 2 inches
    .3) Reflector type? Foil tape
    .4) Is there a consistent fresh air supply? Yes.
    .5) Do you have an exhaust fan and a circulation fan? Only exhaust
    .6) What are the bulb wattages, kelvin ratings, and schedule? 23W at 12/12 (I believe they are 2700k, they are yellow, not the daylight kind)

    Your medium:
    .7) Specific brand and type of soil, (coco, peat based soilless...) and anything you've added to it. MG Potting Mix, no additives
    .8) Size of container. I want to say it is about 2 gallons.
    .9) Did you use peat pucks (or similar) to root clones or germinate seedlings? No.

    Your nutrients and water:
    10) Source of water? (tap, bottled or filtered) What's it's ph before adjusting? Bottled distilled water, pH 6.4
    11) Method of checking water ph. (ph pen, test strips, aquarium test kit...) Drops/tube style test kit
    12) Method of adjusting water ph. (phosphoric acid, white vinegar, hydrated lime, PH Up...) I have been mixing distilled water (6.4) to my tap water (7.5) to achieve the desired pH (~6.8)
    13) Specific brand and N-P-K ratio for each bottle. List dosages (quantity per gallon) and current feeding schedule. Gro-Fine Bloom (10-54-10) 1/4 tsp/gal weekly
    14) How often are you watering between feedings, and how much per watering? I water 3-4 times a week, 6-8 cups at a time
    15) Any additives or tea's? (Superthrive, CalMag, molasses, Mother's Earth...) I use molasses at 1 tsp/gal
    16) Are your ph levels stable, or do they fluctuate? Unknown, my test kit is not good for runoff
    17) What is your ingoing water's ph? ...your runoff ph? Ingoing: 6.8, runoff unknown
    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? Indoors
    20) What size of closet, room or hut? Rubbermaid tub (2ft W x 1.5 ft D x 3ft H)
    21) What are the temps and humidity levels while lights are on? ...With lights off? 84F on, 70F off
    22) Have you seen signs of insects in the growroom? I see a stray gnat now and then.

    Your strain:
    23) What strain are you growing? (Indica dominate or Sativa dom?) I believe it is sativa dominant
    24) From seeds or clones? Seeds.
    25) Is this an autoflower strain? No.

    Thanks a ton for any help =)
  2. Rusty Trichome

    Rusty Trichome Registered+

    Which MG potting mix?
    How long since their last transplant? If you just transplanted, you are overdosing the ladies, and will need to flush well. You have to let the plant eat-up the existing (MG) nutrients before adding your bloom ferts.

    Sounds like Schultz rose food. But I couldn't find the Grow-fine Bloom. I found their lawn products, but no Bloom formula. Some rose foods are low in micro's, but you use molasses, so doubtful that's an issue.
    If it's a powder, are you dissolving it COMPLETELY (for a few minutes) before adding it to the plants?

    How much runoff do you have when watering?
    Before watering...if you squeeze opposite sides of the pot a little, (at the same time) does the soil have any 'give' to it? (does it squish, or is it a solid, unmovable brick?)
    After watering...same question.
  3. Ziggilus

    Ziggilus Registered

    It's been about a month since they were last transplanted.

    Strange, I can't find it online either. But on the back it says it contains copper, iron, manganese, and zinc.

    I usually mix up my nutes the night before so they have time to dissolve, but looking at the bottle now there is some stray powder sitting on the bottom of the bottle =/

    It's hard to say exactly how much, I just let it run down the drain. But it usually starts running off after I've added about 4 cups, so I'd say at least 2 cups or so of runoff.

    Right now (2 days after watering) there's a little bit of give, but it's mostly just hard. I can't squeeze it more than a half inch or so. When I water next, probably tomorrow, I'll check again.
  4. Ziggilus

    Ziggilus Registered

    I took it out of the box so I could check this better today. It's pretty much a brick, before and after watering. What does this mean?

    It just says "Miracle Grow Potting Mix" on the bag.

    Also, I know my pH test kit isn't good for runoff testing, but I tried today anyway just to see. My runoff had a slight yellow tinge, but was mostly clear. But when I added the pH drops it turned very very yellow, indicating a pH below 6.0. Could this be indicative of an over fert problem? Or is my test kit really useless for this type of thing?

    Thanks again =)
  5. Rusty Trichome

    Rusty Trichome Registered+

    "The brick" is from underwatering. The entire rootball needs some moisture and air to survive. When you let the medium completely dry out, it will need either a good soaking or a surfactant.

    I slowly add the properly ph'd water. I add a cup, wait a minute. Add a cup, wait a minute. Add a cup.....on and on till the rootball becomes pliable again.
    You can use a surfactant. A surfactant lessens surface tension of the water, allowing for easier absorption into the medium. 1/4 tsp of dishsoap per gallon of water usually does the trick, but never use anti-bacterial soaps. (or it'll kill the beneficial bacteria) One or two applications should be fine, and don't make dishsoap a regular weekly additive.

    Any color coded test will be skewed by the tinting. You likely aren't even in the ballpark of an accurate runoff number. Most likely it's at neutral or slightly lower. (6.7-7.0ish) MG is pre-buffered, and the buffering lasts about 6-8 weeks or so.

    If the bag doesn't specifically say it's the 6 month formula, then it's the regular 3 month mix, which should be fine...if properly watered. I believe I was adding nutrients to my MG soil at about 4-6 weeks. Half doses at first, and watch for the plants reaction.

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