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  • Grape vine iron deficiency mystery

    As some of you may remember, my allotment grape vines got badly hit by frost back in mid-May. They are both growing back nicely now, but on one of them almost all of the leaves are golden in colour, rather than green. I looked this up, and it seems it is almost certainly iron deficiency. Only iron deficiency will make the entire leaf, even the youngest, newest leaves, turn yellow like that. Other deficiencies cause inter-veinal yellowing or mottled yellowing, as too do any diseases which can cause yellowing.
    What's odd is that I am at a loss for what caused it to suddenly be deficient of iron. The previous growth, before the frost came, was green and healthy, and the other grape vine, grown just a few metres away on much the same soil, is green and healthy, as are the grape vines on other people's plots. It's just this one. I suppose the dry weather is a possibility, but I think I've been keeping it fairly well-watered.

    I plan on buying some sulphate of iron, both to add some to the soil and dissolve some in water to use as a foliar feed, and I've already given it a dressing of poultry manure, but I'm slightly concerned about what might have caused this, and whether it can be trusted to go away on its own with time and feeding.

  • #2
    Maybe you have a local patch of soil with a high pH. So no matter how much iron is in the soil, it isn't actually available to the plant.

    It is very strange, though, that this should have occurred after the frost plus not in previous years.

    Have you tested the soil pH just to see?

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    • #3
      I haven't yet, no. I have some test strips, though, so I will test it today (if I remember).

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      • #4
        My auld Dad used to grow leeks in a sloped trench. At the top of the slope he had a pile of old rusty nails which he thought the rain would cause 'run off' and cure any iron deficiency. His logic seemed ok but his is the same fella that fed his leeks with old beer from the local club beer tanks and killed them all off.
        My Majesty made for him a garden anew in order
        to present to him vegetables and all beautiful flowers.- Offerings of Thutmose III to Amon-Ra (1500 BCE)

        Diversify & prosper


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        • #5
          Tested the pH today. It's 7, or possibly 6.5, it's a little hard to tell. Either way, nothing that should cause such a severe iron deficiency.
          I sprinkled 30g of iron sulphate around the root area today and watered it in, as well as spraying the leaves with a 1% solution.

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          • #6
            Good luck. Hope it works for you.

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            • #7
              Three days after spraying it, and the leaves are already noticeably greener. In fact most of them have fully recovered, and maybe only a quarter of them are still yellow.
              I'll keep spraying it once a week for a few weeks, until it has had a chance to start properly absorbing the iron sulphate I added to the soil.

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              • #8
                Hi Ameno and Co,
                I have a few vines myself at the allotment, and felt they were looking a bit yellow all summer. I kinda put it down to the funny start to the growing season we had, but eventually I figured it must be a nutrient deficiency - so I did some research and, sure enough, grapevines can struggle to extract the iron they need in cold waterlogged soil, even if they were fine in previous years. I went and bought some iron sulphate and sprayed it on at a rate of maybe a tablespoon per litre over the weekend (a few hours before the thunderstorm!), so I went and had a look today and all the leaves have little black specks! I'm wondering if I may have put it on too strongly? Or would it be a fungus that has just appeared either? Did you notice any funny spots after spraying yours?

                I got a little bit paranoid and gave them another spray with magnesium sulphate today, I need to put the sprayer away!!
                Cheers

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                • #9
                  1 tablespoon to a litre may have been a bit too strong. A 1% solution is what you want to aim for, and 1 level tablespoon is around 15g, which makes for a 1.5% solution, and if the spoon was rounded or heaped then that would be more still.

                  The brown spots could also be caused by the nutrient deficiency itself. Sometimes deficiencies can cause small necrotic patches (patches of dead cells) in leaves.

                  Without a picture I couldn't say anything more precise.

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                  • #10
                    Here is an example of the black spots, upon closer look this evening I think it must be specks of iron or staining from the spray. The leaves really look to have greened up though! Hopefully I haven't overdone it too much. It will be interesting to see if the leaves assimilate all the black spots or will they remain like that for the season. Or get worse, hopefully not! There are some slightly burnt looking patches on some leaves too. I must commandeer the kitchen scales for my next foray into crop protection!

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