Chill hours, how much do they matter?

[Levar]

Here’s a great tool I just found:
http://www.getchill.net/

It calculates chill hour accumulation within a given time frame based on info gathered from wunderground.

And yeah, Miami accumulates 0 chill hours on average lol

[Richard]

Here’s a great tool I just found:

http://www.getchill.net/

It calculates chill hour accumulation within a given time frame based on info gathered from wunderground.

In some populated regions of the world chill hours can vary 50-200 hours every square mile.

[Isaac-1]

Richard, I am sure that is true, but I suspect most of those have either major elevation changes, or they are near a large body of water.

[Levar]

I didn’t know it could be so variable. That’s great to know.
The wunderground map appears to have tons of stations, though. I wonder how effective getchill is for useable data collection.

[Richard]

I suspect most of those have either major elevation changes, or they are near a large body of water.

Well yes, California does have variable elevation and many locations are close to lakes, streams, or the Pacific Ocean.

[Olpea]

The life span of commercial peaches in the US is very short because growers expect very high productivity and they can only get it for 15-20 years before they burn out their trees. Peach trees in China can be productive for hundreds of years. American growers don’t care because by their standards the Chinese trees are not producing enough fruit each year and of course any fruit produced after you’re dead doesn’t count at all to an American grower. And China is not an outlier.

It’s true commercial growers in the U.S. push trees hard, but China also has intense peach production. https://www.youtube.com/watch?v=6rT-2HId7Fg

The trees hundreds of years old in China are the result of species differences (i.e. the old Chinese trees are not prunus persica, but rather prunus mira, or prunus kansuensis). Cultivated persica trees in China only last about 10 years, according to Desond Layne in the above link.

About a year ago, there was a discussion about the “wild” Chinese peach trees on the fruit forum.

Aging of a peach tree

I know that generally peach is not long living tree. My is about 8 years old now, and if not counting this year "no crop" issue(due to the weather) it is doing OK and still put some significant grows this year. My question is, when peach tree getting old - how do you know it? Does it slowly decrease production, or suddenly dies? If it is production issue, can the branch be grafted on, or may be it is old root stock you can graft on, or the roots get weak and the tree just has to be replaced?

[Richard]

To my knowledge, the shorter life span of Peaches in the south US is due to pests and horticultural practices.

[alan]

To my knowledge, the shorter life span of Peaches in the south US is due to pests and horticultural practices.

Don’t forget about weather. I didn’t grow peaches when I lived in CA- almost no one did in my area did, but when I moved there in '63 there was a stunted apricot tree in my yard. One year our grey water line sprouted a leak within its rootsystem and it began to take off. It was the tree that got me started on what turned out to be my life’s career and it was still thriving when my father died 5 years ago.

Years later I observed naturalized apricot trees that might have been 100 years old growing near the Rio Grande in New Mexico where they are common. If you want such majestic old fruit trees here you have to settle for pears and apples. They survive our extreme weather much better than stone fruit- especially cots. Given how apricots survive the very high desert where there are wide swings in temps, my guess is humidity may be partly responsible for the lack of toughness here.

However, UC Davis still says peaches are no longer profitable after 15 years (I assume that’s what they mean by life-span). The quality of fruit on old peach trees can decline as well as quantity- a certain amount of vigor is needed to size them up.

[Olpea]

Alan, you’ve mentioned you used to live in CA and have mentioned family there. I’m curious, can you venture to guess the oldest back yard peach tree you personally know of in CA.

I thought it interesting Greenmantle Nursery mentions a 50 year old peach in his orchard as unusual. Greenmantle is in northern CA. The owner told me they have lots of rain in the winter, but they’re summers were bone dry with little humidity.

About 25 years is the oldest peach tree I’ve seen here.

http://www.greenmantlenursery.com/fruit2008/peaches2008.htm

[castanea]

The old trees in China are mostly prunus persica, the common peach. The other two species are rarely found. And of course China grows peaches for intense production as they do almost everything else. That’s not what I am talking about. The older prunus persica are sometimes seedling trees or are grafted onto prunus persica seedlings. They can live a long time. Peach trees that are planted in commercial orchards in China today, like similar orchards in the US, are not planted on prunus persica rootstock. That’s one of the major reasons they don’t live so long.

[alan]

I was only aware of one peach tree in Topanga and it was growing in the “arctic belt” that got the most freeze events anywhere in the vicinity. I actually helped take care of fruit trees at that site almost 50 years ago but I don’t know the fate of that tree.

[Olpea]

The old trees in China are mostly prunus persica, the common peach. The other two species are rarely found.

In terms of peach trees hundreds of years old in China, could you point me to any documentation that the long lived peach trees in China are persica?

The older prunus persica are sometimes seedling trees or are grafted onto prunus persica seedlings. They can live a long time. Peach trees that are planted in commercial orchards in China today, like similar orchards in the US, are not planted on prunus persica rootstock.

I don’t doubt grafting persica on some other prunus species may shorten life, but that is not the issue in commercial production in the Midwest, Northeast, or even the Southeast, in the U.S. In the regions mentioned, peaches grafted on persica are by far the norm. I don’t think grafting peach on persica is a pivotal factor in the longevity question.

[castanea]

The old trees in China are mostly prunus persica, the common peach. The other two species are rarely found.

In terms of peach trees hundreds of years old in China, could you point me to any documentation that the long lived peach trees in China are persica?

The older prunus persica are sometimes seedling trees or are grafted onto prunus persica seedlings. They can live a long time. Peach trees that are planted in commercial orchards in China today, like similar orchards in the US, are not planted on prunus persica rootstock.

I don’t doubt grafting persica on some other prunus species may shorten life, but that is not the issue in commercial production in the Midwest, Northeast, or even the Southeast, in the U.S. In the regions mentioned, peaches grafted on persica are by far the norm. I don’t think grafting peach on persica is a pivotal factor in the longevity question.

Peach tree short life (PTSL) is a problem peach trees have in the US. It is not a genetic component of peach trees to be short lived. PTSL is not fully understood but appears to be related to the numerous bacterial diseases and nematode problem peaches have in the US, problems which American rootstocks have either not solved or have exacerbated…

Most discussion of Chinese fruit and nut trees occurs in Chinese publications. I don’t read Chinese. My knowledge of Chinese trees comes from multiple visits to China. For example, during a visit to Northwest A&F University in Yangling in 2016 for the first international apple symposium, we saw 200 year old fruit and nut orchards between Yangling and Xian, and examined numerous old fruit trees around the A&F campus. We saw many old peach trees which were identified specifically as persica. It was difficult to tell whether they were grafted or not. Chinese researchers are now doing some hybridization between persica and the other species but that is a relatively new practice. Persica is the tree used for peach production and has been for hundreds if not thousands of years and they can grow to be quite old.

Peach trees in the US are short lived because of production practices, diseases and because of the rootstocks used. It is not because peaches are genetically predisposed to be short lived. I had assumed that Lovell and Nemaguard, the most common stocks used, were not pure persica because they have so many problems, but I just looked them up and they seem to be pure persica. They just don’t have enough disease resistance. That’s why the USDA in Byron Georgia developed the Guardian rootstock which is now being more widely used. That should increase the productive life of American peach trees.

[alan]

It is not a genetic component of peach trees to be short lived.

What do you base this statement on beyond your anecdotes? To me peaches bear all the hallmarks of a pioneer type species- very early bearing, weak branches ,very vigorous growth but little growth out of old wood. Live (grow) fast, die young. That occasional trees live a long time is not proof of the general longevity of the species.

Because your statement is so contrary to the general literature it needs some academic enforcement to be interesting to me.

I manage some 150 year old apple orchards with many trees still productive in the original rows. PTSL is an issue in the south only, as far as I know- not in the U.S. as a whole, but peach trees never seem to live beyond about 30 years here.

[Drew51]

What do you base this statement on beyond your anecdotes?

I would say he is correct else we would not be cloning to propagate. As far as i know plants know their biological age. Demonstrated with bamboo once when every single clone flowered on one cultivar and proceeded to die all across the country. Most flower about every 140 years, and every clone flowered when it hit that time, big or small. So the Indian Free in my backyard is probably 300 years old, if not from a recent seedling, which is very possible. Although we know you can clone these just about forever. So I would say this proves it’s environmental not biological. If biological clones should have no vigor and never really thrive. So far that does not happen. How do the genes know they are from a big tree that lost all vigor, or a cutting that was budded and has loads of vigor? They do not, it’s environmental.

The symbol of a peach tree in China stands for longevity.
http://www.nationsonline.org/oneworld/Chinese_Customs/flowers_symbolism.htm

[Lizzy]

Galaxy (another low chill cultivar) blooms very early. So early I’ll probably remove it.

Ugh, yes @Olpea, out here in California Galaxy never even goes dormant. Mine currently still has some leaves from last season, and the new buds are breaking. Drives me crazy. But the real problem is that here, the skin separates from the stem and rot gets in. It’s a vigorous grower, but I didn’t get one single good unrotted peach from the big galaxy branch on my multi graft seedling. It’s getting grafted over!

[castanea]

As posted above, peaches have numerous diseases and other problems when growing in the US, particularly when growing in the SE US. Their life span in the US is meaningless. Their life span in China is what is relevant. Peach trees originated in NW China in an area with a cooler drier climate than what we find in many peach growing areas in the US. When subjected to hotter more humid weather they get more diseases and thus live shorter periods of time. Somehow Americans have gotten the idea that peaches love growing in the SE. They do not. Here are a couple of photos of a 1000 year old peach tree in China.

[alan]

You are funny Drew, and by your reasoning concerning clones, which cloned fruit trees are short lived?

Castanea, I am unsure of the genetic relationship of the tree in the photo to the peaches we grow here, but thanks for posting the photo, it is beautiful.

[Olpea]

Peach trees in the US are short lived because of production practices, diseases and because of the rootstocks used. It is not because peaches are genetically predisposed to be short lived. I had assumed that Lovell and Nemaguard, the most common stocks used, were not pure persica because they have so many problems, but I just looked them up and they seem to be pure persica. They just don’t have enough disease resistance. That’s why the USDA in Byron Georgia developed the Guardian rootstock which is now being more widely used. That should increase the productive life of American peach trees.

Guardian was released about 25 years ago. It’s not the answer to peach longevity. I’m unconvinced rootstock makes the difference. I’ve had/have peaches on virtually every commercial peach rootstock available in the U.S. (Lovell, Halford, Bailey, Starks Redleaf, Guardian, Tenn. Nat., and lots of peaches on my own seedlings). I have also raised peaches on a few plum or plum hyrbrid roostocks K1, St. Julian, Citation, and I think K86. Rootstock is not the difference. We don’t even have PTSL here. I think we can be pretty sure if it were something as simple as roostock to peach tree longevity, someone in the U.S. would be doing it.

So the Indian Free in my backyard is probably 300 years old, if not from a recent seedling, which is very possible. Although we know you can clone these just about forever. So I would say this proves it’s environmental not biological.

Drew,

Scion wood doesn’t have a biological clock. Does scion wood even have telomeres? Either way, it’s the whole organism which determines the life of the tree. Trees as an organism have a biological clock, and it’s different for different species. There are redwoods 2000 years old, doesn’t mean there are any pear trees which can live that long.

As posted above, peaches have numerous diseases and other problems when growing in the US, particularly when growing in the SE US. Their life span in the US is meaningless. Their life span in China is what is relevant.

Castanea,

The picture you posted looks suspiciously like the pics shown in the previous thread I mentioned (prunus mira, or prunus kansuensis). I’m not trying to be contentious but I reject the idea that peach trees (persica) can be inherently long lived, and that it’s just that we don’t have the right climate here (any climate in China can be found in North America). I doubt it’s just that all the published literature is only in Chinese. Persica trees living hundreds of years would hardly be able to be kept secret.

Show me a tree with a trunk the size of the pics I see from prunus mira, which has actually red fuzzy peaches on it, and I will shut up. Strangely, the only pics I see of the “legendary” peach trees only show flowers.

[Lizzy]

I’ve been thinking how silly it was of me to spend so much time grafting all sorts of stone fruits to the peach I grew from a peach pit back in 2004, since it’s now 13 and might not have much life left in it. But if it’s true that seedling peaches are longer lived, I’m in luck! I will report in a few years if it starts to die. It’s not super-healthy now, but that’s probably because I really haven’t fed it anything, since I had to be away during the crucial months last year, and in years before that I didn’t understand how much food trees need. I’ve learned that from this forum.

The grafts on it of vigorous stone fruits, like Dapple Dandy, still grow like gangbusters, though.