North American Fruit Explorers mailing list at ibiblio

["Lon J. Rombough" <lonrom@hevanet.com>]

I don't use the practice myself - it's done commercially.  However, it's not
necessary to take a huge number of leaves off - just a few in the zone where
the grapes are.  Leaves all over the vine contribute carbohydrates to the
fruit. (Grapes don't behave the same physiologically as fruit trees).  One
good example of the difference is that if you girdle a fruit tree, it's
dead.  If you girdle a grape vine, you've cut the phloem but not the xylem,
which makes up most of the wood.  The xylem can still send water and
nutrients up to the leaves, but the food made by the leaves can't go down to
the roots (one of the main storage areas) so it backs up and goes to the
fruit.  That's why girdling will increase the size of grapes and increase
the set (when done before or just at bloom). 
Meanwhile, the wound heals, the phloem reconnects and the vine is back to
normal, but with bigger fruit.
-Lon Rombough
Grapes, unusual fruits, writing, more, at http://www.hevanet.com/lonrom
 
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>From: edforest55@hotmail.com
>To: nafex@egroups.com
>Subject: [nafex] Re: Sour Grapes, Sweet Corn
>Date: Thu, Aug 10, 2000, 5:03 AM
>

>Lon,
>You wrote about pulling the leaves off to let in light to the actual 
>grapes, apparently Lon, you don't think that loss of leaves near the 
>clusters will result in any significant loss of sugar being sent to 
>those grapes in its immediate proximity. Can you tell me which leaves 
>supply most of the sugar to the fruits, that is how close do the 
>leaves have to be to the fruit to be able to send sugar to them? Or, 
>lets say that there were only one fruit on a tree, then all of the 
>leaves were defoliated on that side of the tree, would the leaves on 
>the other side be able to transport the sugar across the tree to that 
>fruit? Would they be able to transport them from a near branch? Or 
>even closer, say from just a few feet from the fruit on the same 
>branch? I remember Ed Fackler saying that the amount of sunshine on 
>the leaves in spring determine how many blossoms there will be the 
>following spring. And that one can foliar feed the leaves right near 
>a fruit with nitrogen to increase its size and ability to manufacture 
>sugar and I guess that this gave me the impression that there are 
>just a few leaves near the fruit that supply the sugars to that 
>particular fruit. I've always been unclear on this. (I do understand 
>that the tree has carbohydrate "sinks" and that the carbos go to the 
>sink that is most in need at certain times, but I guess the question 
>is how flexible is the tree to send carbos across the branches, up, 
>up and down, down only, across, across on just one branch, from 
>branch to branch, (boy this guy asks a lot of questions) 
>Kevin B
>
> 
>". . . do some leaf pulling - pick off
>> leaves just around the fruit clusters to let more light to them.  
>This
>> doesn't really help them sweeten any more, but it can help them dry 
>off
>> after rain to reduce the likelyhood of disease."
>> -Lon Rombough
>
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