[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
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.
NEW grape pruning video: http://www.bunchgrapes.com/dvd.html View a
short, low resolution clip here:
Grapes, writing, consulting, my book, The Grape Grower, at
http://www.bunchgrapes.com Winner of the Garden Writers Association
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A video about 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
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
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
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!
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