Muscadines: which deficiency

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Dec 16, 2019
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I have bought 2 muscadines from Ison's 2 years ago: an Ison's and a Magnolia.
They have been put in the soil and kept protected during winter, as here in Graz, Austria, winter temps can go as low as -20°C.

Soil composition is clay, enriched with lot of humus and fertilized with ripe manure.
The leaves of one of the plants are showing for the second year a characteristic yellowing in the intra-vein parts, turning white or slightly brownish/burnt with time.

To address this I have given soil and leaves amendments.
The first summer I gave iron chelate (preparation for lemons).
The second summer I gave magnesium sulfate (Epsom).

In both cases no improvement was visible.
The plants are quite close. In the attached pictures you will see yellowing leaves from one plant and darker leaves from the second variety.

Does anybody know what may be the problem?

Thanks, Leonardo
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Can't see your pictures......try using triple 13 fertilizer,,,handful on 1st of month and on the 15th add handful of calcium nitrate to each plant.....may be lack of fertilizer.
Sorry for the images, I think I made a mess with trying to delete the duble post.
Here are the leaves, toward the end of summer

So you think the 3x13 fertilizer may help in the beginning of the season, and the calcium-N after 2 weeks?


This year I gave NPK fertilizer, and some more magnesium.
Problem is gone. The plants have grown much more and the first flowers and fruits appeared!
Thanks to all for the hints.
Clay soils with bad drainage or too much water will make it worse. I've got 2 vines about 10 ft apart one had the same problem shown in your pics other looked fine - the difference was drainage in my heavy clay soil. I relocated a roof drain and it has improved.
Hmm... the low temps are a concern. Unfortunately clay based soils do the opposite in terms of warmth. They reflect heat. A more sandy/gravel type of media mixed in will both help with drainage and help absorb warmth for you.
As an added/optional layer some local adaptations I employ here for more cool loving and pm susceptible varieties is the use of a canopy/large tree and mounding.

Canopy keeps the rain off of it and using a mix of clay and fine wood shavings reflects heat yet allows water in and out to further cool via evaporative effect.

For more heat loving varieties I do an inner mound of gravel, sand, some loam and wood shavings then just wood shavings and clay for the outer layer bc once it hardens keeps the inner mound in tact from erosion.

Perhaps a combination of both of these would help you as well. The heat absorbing mound to help preserve the trunk from freeze damage and hence the scourge that is crown gall and a tall evergreen as a canopy to keep frost off of it.

One thing to add Would be use of mulch for insulation.

Something like a pine or cedar I believe would be ideal although you may have to trim off some bottom growth to Taylor the amount of sunlight that can be let in.

The accumulation of needles would be a great insulator and over time them breaking down into the soil I suspect would be ideal nutrition for a muscadine
Depending on the location and height of the canopy they would still get full sun in the mornings and evenings; just not the mid-day sun.

This should be sufficient for the vine to grow and be healthy keeping in mind the requirements for growth are close to half as much as the requirements for ripening.

additionally you could place the trunk close to the edge of the canopy and train your fruiting growth to ‘peek out’ from under the canopy to get that all day sun to ripen the fruit.

Such a suggestion is only applicable to you if you have a few vines and not planting a vineyard, etc.

Depending on the location you’d have to trim approximately 8-12 feet of branches from the bottom of your tree.

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