[NAFEX] brown tor resistance, was: Plum Curculio Resistant Cultivars

Anton Callaway marillen at earthlink.net
Thu Nov 15 06:38:31 EST 2007


Resistance to brown rot in peaches is very interesting.  I'd love to hear more details about this Brazilian peach and the mechanism of resistance.  For instance, is the rubbery flesh a coincidental phenotype or is it part of the resistance mechanism?  Does this resistance hold up even when curculio control is less than complete?

About split pit:
Thinning, especially early thinning of early peaches leads to dramatic increases in fruit size.  The increase in fruit size increases the distance calcium must travel to the developing pit, where it is needed for proper hardening.  Early peaches are especially prone because the development happens so rapidly that calcium transport must be especially efficient.  The studies I've seen on effective methods to reduce split pit recommend increasing calcium availability to the trees, by soil amendments and foliar spraying of chelated calcium and by switching to own-rooted trees for new plantings.  Calcium chloride should work to some degree in foliar sprays and it is cheaper and more easily found.  However, the chelated calcium was the most effective.  The tested forms of chelated calcium included acetate, lactate and gluconate.

Anton
Zone 8
It's finally raining!!! (a little bit)

-----Original Message-----
>From: Douglas Woodard <dwoodard at becon.org>
>Sent: Nov 14, 2007 5:00 PM
>To: North American Fruit Explorers <nafex at lists.ibiblio.org>
>Subject: Re: [NAFEX] brown tor resistance,	was:  Plum Curculio Resistant Cultivars
>
>Some years ago the Pomona had an item about a Brazilian peach which is 
>resistant to brown rot. I talked about it to a breeder at the Vineland 
>station near me. He told me that they were doing breeding of canning 
>peaches with its pollen which they had obtained from California where 
>there was an active breeding program using the Brazilian peach. He also 
>said that they were only working on canning peaches because the 
>Brazilian peach was a rubbery fleshed type which would need several 
>generations to get the brown rot reistance into a good quality fresh 
>eating freestone peach. I haven't heard anything about this work since.
>
>I have been told by a grower that thinning peaches when the pit is still 
>jelly-like results in the pit rotting quickly on the orchard floor and 
>not carrying the brown rot infection over to the next year (at least 
>from that source). If you thin when the pit has hardened it does not rot 
>away completely and will carry the infection to the next year. This 
>makes the thinning of very early peaches difficult; apparently if you 
>thin early you get more split pits  - harbouring rot and unsaleable - 
>which earlies are prone to anyway.
>
>I believe the Harrow apricots were also selected for brown rot 
>resistance to a degree.
>
>Alan Haigh wrote:
>[snip]
>>  
>> I'm also curious about brown-rot resistance in stone-fruit.  This is 
>> going to be very regionally specific, I'm afraid, but maybe we can all 
>> learn something.  I have read that the Seneca plum is resistant but not 
>> found this to be true.  I have observed that in peaches older varieties 
>> seem to have more resistance.  Encore, Autumn Glo and Lady Nancy tend to 
>> rot without significant protection but Elberta and Belle of Georgia do not.
>>  
>> In southeastern NY earlier ripening stone-fruit that face less heat and 
>> humiditity suffer less from brown-rot and peaches less from scab.
>> So many of the newer peaches are highly susceptible to brown-rot that I 
>> think we should limit the discussion to what's resistant, not what's 
>> not, unless it's a variety that seems to exist to rot.  In newer 
>> peaches, varieties from the Harrow series are evaluated for brown-rot 
>> resistance but they are falling out of popularity.
>
>[snip]
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