[NAFEX] Giberrellic Acid treatments on dwarf peaches [SEC=UNCLASSIFIED]

Lon J. Rombough lonrom at hevanet.com
Wed Jun 17 20:13:30 EDT 2009


GA has uses in helping seeds break dormancy, but it's not something I'd 
recommend for home growers to use indiscriminately.  On fruit trees it 
may affect the tree similarly to herbicide, causing deformation, 
dropping of leaves, and worse.  Or have no effect.  Much better to have 
a variety that performs well without GA than to try to trick a poorly 
adapted type.
And it's NOT something to try on grapes without some careful 
experimentation.  That increase in berry size from GA is just like 
leaving extra fruit on the vine and it's very easy to overcrop a vine 
using GA.  Then the fruit won't ripen well and the vine is unable to  
harden it's wood as well as it should.  As Karl notes, timing and 
application strength are crucial.  Not something to be  done casually.
For a home grower who wants to experiment with increasing the size of 
seedless grapes, there are much safer methods, including girdling of 
single canes, or a combination of pruning and thinning that's written 
up in The Grape Grower.
-Lon Rombough
NEW grape pruning video: http://www.bunchgrapes.com/dvd.html View a 
short, low resolution clip here: 
http://www.youtube.com/watch?v=8Q58zFY0B1M
Grapes, writing, consulting, my book, The Grape Grower, at 
http://www.bunchgrapes.com  Winner of the Garden Writers Association 
"Best Talent in Writing" award for 2003.
A video about The Grape Grower : 
http://cookingupastory.com/index.php/2008/04/18/the-grape-grower/
On Jun 17, 2009, at 5:01 PM, ADAMSON, Karl wrote:

Since we are talking GA, has anyone used GA on dwarf peaches (I'm not
talking dwarfing rootstocks but the dwarf mutants)?  I'd like to fast
track the growth of my dwarf peaches by treating them with GA when they
break dormancy next season.

In reply to Melissa's query on grapes and small organic produce:
Sam is correct its Gibberellic acid (GA) that's used.
Its basic action is to make cells grow much larger (in only the
lengthwise direction).

In grapes it can serve a number of functions.
1) At -25 to -5 days preflowering its used mainly to lengthen the
bunches (this can facilitate drying when ripe and open up tight
varieties)
2) Sprayed at -5 to 0 days preflowering it thins bunches and promotes
seedlessness (less grapes larger overall size)
3) Sprayed 0 - 14 days post flowering when the fruit cells are
proliferating it expands these cells so the fruit can eventually grow
much larger.

You also get some maturity alteration depending on when you spray.
This must all be done in conjunction with normal commercial vine
management and it must be noted that GA's effect is variety dependent,
some varieties do not react to it in a commercially beneficial way.

In the backyard, a harsh combination of pruning, bunch thinning/tipping
and girdling can produce a grape that rivals GA treatment, but why
bother, it just means less fruit and larger targets for the birds!

Karl
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