North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

After submitting my question to another forum I was forced to conclude that most of my guesses below are probably wrong based on some very useful responses.  The main problem was probably just the frost damage that left only fruit beneath the canopy.

One grower who responded measures his fruit regularly for brix and says his under canopy peaches consistently read out at 50% the brix of his better exposed fruit.  Peaches are the only species where he finds such a dramatic difference.  He is a Texas fruit grower and says temps must get above 110 F to damage peaches.  

I think I'll start removing all UC peaches at thinning time.  Might start measuring brix as well.  What the hell, I'm supposed to be a professional.

On Wed, Sep 1, 2010 at 9:52 AM, Alan Haigh <alandhaigh@gmail.com> wrote:

Last season in southeastern (but not coastal), NY we barely had a summer, with June and July providing the weather of a cool, wet April and May.   In summary, 5 months of a wet spring with one month of summer followed by a warm, sunny autumn.

So why would I expect peaches last year to be consistently rich and sweet?   I didn’t and they weren’t.   In fact the early season brought peaches so poor they were only useful for compost.

This year, however, was the absolute opposite, with an early spring followed by exceptionally dry, warm, and bright days from mid-May through August.  So I was expecting excellent quality from the peaches that survived a nasty late frost- in other words, a light to moderate crop with excellent quality.  Boy was I ever wrong!

The weather’s been hot, but nothing beyond what would be normal in Georgia, temp-wise.  A couple days pushing 100 degrees, I guess, and consistent temps in the high 80’s and 90’s for the most part.   Georgia grows great tasting peaches in similar heat, so why have mine been mediocre, with a few exceptions within any given tree?

I figured at least my Elbertas would be outstanding.  After all, Elberta is the variety that launched the entire peach industry in Georgia.  But they are ripening now (about 10 days early) and they are not very good with greenish flesh and poor sugar.

I have 2 possible explanations.  One is that the frost spared peaches positioned beneath the canopy, where even with summer pruning, it was difficult to give them great exposure.  Included in that explanation is the possibility that I over pruned them a bit to compensate.  The other is that it wasn’t Georgia heat we were getting at all.  There were lots of low humidity days resembling the interior valleys of CA- oh and there was also the epidemic stink bugs.

Anyway, I’ve long known that later season CA peaches have a strong tendency to look beautiful but taste sucky.  I assume this is the result of the very warm days that tend to arrive in CA peach growing country by July.  Peach production in that state has been pushed ever more eastward as land closer to the coast is developed or turned into vineyards.  This subjects the trees to higher and higher temps and also lower humidity.   

My theory is that low humidity heat has more of a tendency to cook fruit on the trees and damage their quality than high humidity heat- in other words, for peaches and other fruit, the old cliché would be changed to “it aint the heat, it’s the lack of humidity".