fertilizer burn on young maple?

Discussion in 'Maples' started by dawgie, Jun 9, 2005.

  1. dawgie

    dawgie Active Member 10 Years

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    Location:
    Raleigh, NC
    I bought several newly grafted Japanese maples in 3-4" pots this spring and transplanted them into 1-gallon containers with good potting soil (Metromix) as soon as they arrived. They all appear to be doing well except for the Emperor. Its leaves burned around the edges soon after planting, which I initially attributed to getting too much sun too quickly. The maples are located on my deck on the north side of my house, where they get some morning and midday sun but shade all afternoon.

    The Emperor recently put out new growth on all of its branches, but the leaves appear to be misshaped and some of them are blackened at the tips. The tree is well shaded now, so I don't see how it could be leaf burn. That leads me to suspect that the tree might be suffering from too much fertilizer. I lightly fertilized the tree with a small amount of slow release fertilizer about 2 weeks after potting it. However, the pot was a used ceramic pot that had a ring of crustiness around the inside top edge, which may have been excess fertilizer that accumulated during its previous use.

    Could this be a reasonable explanation for the leaf burn? There doesn't appear to be any pest problems. None of the other maples I received have shown similar problems, but they are all growing in new ceramic or plastic pots, using the same soil mixture. Should I try repotting the maple now, at the risk of disturbing the roots while it is putting out new growth, or just wait until fall?
     
  2. PoorOwner

    PoorOwner Active Member 10 Years

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    I have had leaves burn on bigger maples from 2-5 gallons, from what I have read and experienced, the sun is not the only factor, if it is getting blasted with west winds the leaves seem to burn up sooner or later. But to be honest those that had most burns are plants with compost blended along with miracle gro potting mix (fert. added). So yeah, nitrogen would probably have something to do with it.

    The plants you had received had a root system slightly bigger than a shot glass. It's likely the nitrogen stimulated too much top growth for the roots to handle now. What I did with my 4" maples (same source as your plants) was untangle the 4" rootball and put it in 1 gallon pot. Didn't apply compost or fertilizer. My plants are not really growing but I'm keeping it moist. Once it grows more roots I am sure top growth will take off.

    I would take it out of the pot and remove any fertilizer granites that I can find.. as I usually do with store bought maples anyway. Replace with new soil.. keep it out of west wind and sun and hope for the best.
    BTW does your potting soil have a pre-mixed fertilizer too?

    In summary I would say that my small maples that are using a lean potting mix and out of western exposure are doing best.
     
  3. Idacer

    Idacer Active Member Maple Society 10 Years

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    Put the Fertilizer Down and Back Away!

    I too am seeing a considerable amount of leaf burn on many of my potted JMs this year. Considering the fact that we've had an unseasonably cool, wet spring (yet to hit 90 degrees) and the sheltered environment that my trees get to live in, I have little to attribute the burning to except for some experimentation with granular fertilzer earlier this spring. I topdressed several of my potted trees with about a teaspoon of a 9-9-9. Won't do it again.

    Trees in the ground? I haven't seen any similar problems even though they were fertilized at least as much or maybe even more.

    Bryan
     
  4. Layne Uyeno

    Layne Uyeno Active Member 10 Years

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    This is one of the reasons I stay away from granular ferts. Too easy to overdo it and burn. The dosage recommendations on the fert container are sometimes too strong for certain plants. Best to play it safe and half or quarter the dosage. Also, chemical ferts contain salts in them and this may cause some burning too. Personally I like organic liquid ferts.

    Layne
     
  5. dawgie

    dawgie Active Member 10 Years

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    Re: update

    Here's an update on my Emperor maple with deformed leaves, presumably from over-fertilization. I transplanted it to a slightly larger plastic pot with some fresh soil, taking care not to disturb the roots. Brushed away old soil near the top, where fertilizer might have been concentrated. Three weeks later, the Emperor has rebounded tremendously. It has put on 6" of new growth with healthy-looking, deep red leaves. The old ceramic pot I had originally planted it in was encrusted with fertilizer that apparently was too much for the young maple.
     

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