Leaf Curl problems - The Claw

Discussion in 'Sick Plants and Problems' started by greenland, May 18, 2006.

  1. Hi all,

    Many of our plants are exhibiting serious leaf curl, affecting young and old plants. The leaf curl does not extend to the older light leaves, or those that were healthy before the leaf curl began. Once the leaf curls, it dries from the outer edge and eventually crumbles.

    The lighting is 800W - 400HPS + 400MH.

    Water pH is tested daily and always within 6.2 - 6.9. Plants are soil based with a mix of potting soil, sphagnum moss and perlite. The potting soil is similar to Miracle Grow potting soil.

    Plants that get grow fertilizer, receive it only on watering days. The fertilizer is a hydroponic liquid mix that is used at its lowest if not lower mix ratio, since leaf curl problem. The young plants, such as that in the attached pic, have not been fed, even though they are now in their fifth week. As you can see, once leaf curl happens, growth is severely stunted. New leaves never get big, just curl and burn up. Bud pistols get red prematurely and resin never builds up. We have lost several plants so far.

    Since leaf curl has come on, all plants have been water flushed, some more than once. Cal/Mag has been added to grow and bloom fertilizer applications for one week now, in case the plants have experienced lock out, but not sure if the cal mag is working.

    From our research, it seems to lead to chemical burn, but we are pretty sure that the young ones were not fertilized, so how could it have affected all? The lights are on a 20 hour regimen, which has been the case during healthier crops, but thought I should mention it anyway, especially if an 18hr cycle would be better.

    We have checked around and can't find similiar pics or descriptions. Any help will be greatly appreciated.

    Attached Files:

  2. can you get me a closer pic of one of the blades, top down, straight on?

    what are the other details of your grow? soil? what's the mix of the soil? how often and how much water?
  3. Hey Greenland,
    Welcome to the City. That is some pretty bad curl there. In addition to up4's questions I have some of my own. When you say the water PH is between 6.2-6.9 is that the water that you give it or the runnoff water? More importantly than the waters ph, what is the PH of the soil itself? Lets rule out PH completely first and then we can figure what else might be wrong. I wonder if since you have not fed some of them if this could be the start of N deficiency but, this curl is awfuly extreme considering we don't see any yellowing yet.
  4. Thanks for the quick response. More pics are included, one is the baby (Northern Lights) shown earlier, the other is a bit older (bag Sativa), about 8 weeks.

    The pH of the water we give it is between 6.2 - 6.9, but that is before adding fert. and Cal/Mag now. We did note that runoff water from one of the flushed plants was 5.5pH. Unfortunately, we don't have any way to pH test the soil. The soil is about 2 parts Miracle Grow soil & Spaghnum Moss, 1 part Scott's potting soil, 1/2 part perlite with earthworm castings on top. We just got a bag of Ocean Forest Potting Soil, an organic mix, that we started to add just to try something new, and cut out 1 part potting soil.

    We did re-pot several plants during the last 2 1/2 weeks fearing that the soil was the problem. We switched from smaller pots (6") to 8" and those that were in 8" pots we moved into 12" pots.

    The fertilizer we use is Flora Nova 2 part. We water when pots show dryness, about every other to every third day. Overall, about 24 plants are watered with about 1 1/2 gallons of water in a session. The room temp is always around 76F.

    Attached Files:

  5. Aha.
    Just as I suspected. 5.5 is way too low. I think you have a ph problem. Go to the local Hardware or garden store and for $5.95 you can pick up a soil PH tester that you just stick in the soil and read what it says. I think this is very important for you since you are having these plant problems.
  6. What do you think could have driven the soil pH so low? And what's the safest way to get the soil pH back in balance? Are there certain soilds that cause pH to drop?

    We'll be picking up a soil tester this afternoon, thanks for the heads up.

    BTW, we just did a flush on one of our Sativa babies, and it tested out at 5.7 pH.
  7. yeah, pH is way too low and causing nutrient lock-out.
  8. Considering that low pH is causing the leaf curl, what is the best way to get it back up to normal pH levels? Through fertilizing and Cal/Mag? And will the Cal/Mag take care of the lock out problem, and how long will that take?
  9. fair play they do look pretty funky, never seen that before or that bad anyways.
    good lick tho and hope they recover
    all the best
  10. get some pH up and mix that in with your feeding/watering
  11. any idea as to how high to take the pH and for how long? haven't read anything on this before.

    oh, and thanks
  12. u want ur Ph to be as close to 7 as possible weed does not like acidic soil one bit. If u cant find Ph up then go to any grow shop and get some lime. And if by chance u make the Ph to alkaline then use something like cottonseed meal or coffee grounds to make it more acidic
  13. weed likes acidic soil. But, it only likes slightly acidic soil.
  14. Alright, thanks for all the help. We got the pH up and down and will see if we can turn things around. Hopefully will have some nice pics to post soon.

    Keep it lit.
  15. so, did pH "upping" do the trick?
  16. Just so we are all on the same page, the range of ph you want to shoot for in soil is between 6.3-6.8.
  17. I dont think that this has to do with pH at all tp tell you the truth. I weas attribute this to something more a long the lines of over-feeding. What is the ratio of the food you are using? at the leafs crumbling from outside-to-in, or inside-to-out?
  18. so far we see a little improvement, and for the most part, new growth is coming on without as much curl as previous. we just started raising the pH yesterday, so we'll just have to see.

  19. So you think a ph of 5.7 in soil is ok then?
  20. Is that an acceptable measure for testing the pH fofthe water runoff from the soil as well?

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