Variation in bud break tree to tree?

Being a home fruit grower, like many I don’t have much exposure to mass plantings of fruit trees, so I thought I would ask here for your observations.

I planted a dozen well sized bare root 20th century Asian Pear trees just over a year ago, along with a Hosui and a Shinko. The dozen 20th Century pears were an end of season bundle deal at a great price, otherwise I would have opted for more variation, they are all growing well (except for one that someone ran over while turning around in the drive way (hit and run), which is now less than knee high ), and are scattered around a 5 acre yard.

Anyway down to the point of the question, out of the 12 matching pear trees, 3 random trees appear to be waking up for the spring already after 3 or so weeks of warm spring weather, with the first flower opening today, 2 or 3 more are showing the beginnings of bud break and the other 6 look the same as they did 2 months ago. We are well over the reported chill hour requirements for 20 century pears (350-400 hours, we hit just over 600 32-45F here according ton the online calculators, get chill, etc.).

Is this sort of spread in waking common across trees of the same cultivar, with some trees being 1-2 weeks or more ahead of others in matching conditions? (the 3 that are waking are scattered in different parts of the yard)

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Sounds like a question for @clarkinks :slightly_smiling_face:

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If some are in more direct sun and others in shade it’s possible. If I add black cow manure or woodchips around the base of the tree it can slow down or wake up the tree. All things being equal I have some that the rootstock influences and causes several days of difference in bloom times. The short answer is yes it’s possible they are the same variety.

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The variation depends on how marginal things are, mainly chilling. With marginal chilling everything is spread out. Around here fruit trees bloom over months. Up north say NY everything blooms in a matter of a few weeks. I have bloom from January, low chill nectarines, to July for some apples. In NY maybe a month from the earliest to the latest.

That said my trees of the same variety usually start around the same time, maybe a week apart.

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In my case sites were selected for comparable overall conditions, sun exposure, etc. though 1 of the trees is in a more shaded location, and 2 of them are relatively closer to a large pond which might mitigate freeze exposure some (though they are on the north side of the pond so I expect this to be minimal, none of these 3 are ones breaking bud yet, even though in theory one might think they received slightly higher chill hours.

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One possible answer is they are not the same trees, just sold that way.

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True, they were all bundled together, though only 2 with individual tags. They did also threw in 2 bonus trees, the Shinko and the Hosui each with their own tag, and separate from the main bundle. Of course that is not to say there was not some mistake in the field digging the. The truth is i would prefer if they were other varieties for better variation and cross pollination, though I do have 3 mature unknown european pears, and I anded another Skinko this spring from a vendor selling cheap bare root fruit trees at the local farmers market last Saturday. It looks a bit marginal, with few roots but for $5 what do you expect.

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Here it would be hard to tell from bloom. We seem to go from cold to hot and all my trees pretty much bloom at the same time As hot comes in April and with over 2500 chill hours everything is ready to go as soon as the weather breaks. Even my 250 chill hour tree behaves like all the others.

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Was I pretty much right in estimating one month total bloom for all species and varieties?

At any rate up north after all that chilling it doesn’t take much warmth for everything to pop.

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For here yes, almost everything last year bloomed within a 2 week period. The Romance series cherries were maybe 2 weeks later, still within a month. I have to start keeping track of the bloom info so i can have exact numbers. Here at least i consistently get fruit, maybe not the sweetest, but gratifying all the same to have fruit each year. We have problems here about once every ten years, I’ll take that, not bad.
Their is an amateur weather station about 1/2 mile from me. It is reporting these chills
Less than the station i was using, I switched to this closer one for info.
Below 45 Model: 2010 chill hours
Between 45 and 32 Model: 989 chill hours
Utah Model: 930 chill units
Positive Utah Model: 938 chill units
Dynamic Model: 49 chill portions

These stations are not very accurate, one about 3 miles from me
Below 45 Model: 2544 chill hours
Between 45 and 32 Model: 960 chill hours
Utah Model: 840 chill units
Positive Utah Model: 850 chill units
Dynamic Model: 45 chill portions

Chills me just to look at those numbers! Currently it is 33F 2 pm Sunday
Working outside today i was getting cold. Going back out right now.

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some of my pear trees wake up on the tips from where I pruned first and start growing and then the rest of the tree wakes up and blooms. a week or two later