I have experience with this. Trifoliate orange does go dormant in winter making the scion more cold hardy. The hybrid root stocks never go dormant and only slow growth in winter.
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It appears, from the article you reference, that rootstock influence on bud break date is rather insignificant (at least for apples) and will probably not grant me a safety net of weeks but rather only a few days at best. It was, none-the-less, a good read of an interesting study.
It’s been another crazy winter…I lost most my mulberry crop last year from a late hard freeze, and this year could be even more damaging. Except for my wise persimmon trees, everything has broken bud…Even my jujubes and paw paws are starting to break bud…in February…how crazy is that; In a more normal year my jujubes don’t awaken until around the first of April (here in North Florida). If there is still an upcoming hard freeze in the mix, I will certainly lose more than the Gulf plum and fig tree I lost last year.
nigra mulbs leaf out the latest of all the mulbs(even if grafted on albas), so will try to graft an alba scion, and see if a late-leafer nigra as interstem would cause delays. In effect, it will be an alba rootstoc, then nigra interstem, then alba graft. Unfortunately will have to wait till next year since all our albas have already leafed out.
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I am greatly interested in this topic, especially how it might relate to apricots and other stonefruits.
I seem to recall reading somewhere a claim that Krymsk-1 understocks can delay budbreak for peach scions on top. I cannot cite or corroborate this… but my Harrow Diamond peach on K-1 gave me the best peaches of 2017 after laughing off that year’s harshest of late April freeze events.
I am trialing a combination of apricot cultivars on top of a diversity of rootstocks. Apricots seem to wanna “up and die” here. Late spring frosts or extreme winter cold may have been the cause of my apricots on Citation all dying (including Moniqui, Moorpark, and the vaunted Tomcot). I am hoping the latest-blooming cultivars (such as Zard and Hoyt) and some of the cold hardiest (Westcot and Hargrand) put on top of the most rugged understocks (Manchurian or Lovell seedling peach) can find me a winning combination. I read in one scientific study (that I also cannot seem to find) that apricots have a tendency to decline on Myro. Not a lot of information for cots on Marianna in areas subject to late frosts, but the literature seems dismissive or doubtful of Marianna for that purpose.
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There are many kinds of trifoliates used as rootstocks today and some are complex hybrids, and so not all of them are deciduous but most are cold hardy and can impart cold hardiness to the grafted scion. These rootstocks may delay the bud break of the grafted scion but in fact bud break can still occur early especially if you apply fertilizers in late fall. A little warming trend in the winter can cause flushing when there’s plenty of available nitrogen nutrients. That is why I stop fertilizing of citruses in early August. The cold hardiness imparted is not only the delayed bud breaks or growth flush but also the increased cold tolerance of the leaves and stems of the grafted scion.
But of course all other things equal, the rootstocks that have delayed bud breaks can delay the bud break of the grafted scion. Generally stone fruits, including their rootstocks, that are cold hardier and require longer chilling hours will usually have delayed bud breaks. They might be used as interstems to delay the budbreak of the grafted scion and a length of 10 cm interstem is used to have the desired effect by attenuating the effects of the stock below it (shared by my farmer friend in Spain who is fond of using a lot of interstems for over 20 years now, we used to go to the same Ecology and Plant Physiology classes in UC Davis during our graduate studies).
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Potentially but I doubt that there is any scientific research since it is not a commercial crop.
It has been demonstrated that flowering can vary at least a week on plums, dependent on rootstock.
Source Plum Report
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Great idea! I’ve never heard of anyone grafting an alba to a nigra…It should be an interesting beast!
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OK! Proof positive (at least for plums).
just for kicks, haha
although a bit counter-intuitive from a gastronomical point of view 
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Ha ha ha! My one mulberry tree is composed of many albas, rubras and nigras, sometimes all on one stem.
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Dan,
I have E plums on M2624 rootstocks in a full sun location and have J plums on seedling rootstocks (own root, right?) in a partial shade area.
My J plum blooms about 7-10 days before E plums.
That seems to be opposite to what the Bloom Date table shows.
J. plums are blooming earlier than E. plums. 2 days delay from the choice of rootstock wont change that much.
The explanation is buried deep in the report that I linked but essentially what they show in the chart is how rootstock will affect a particular cultivar. In this case they were testing European prune plums.
Their aim was to help insure farmers against total crop failure due late freeze and other weather anomalies. For example if you plant half your commercial field with Improved French Prune on Fortuna roots and the other half with Improved French Prune on CTRL9 roots it will stagger the bloom date by a week.
Thanks for your reply. I admit, more than half of the rootstocks on that list, I’ve never heard of. Good to learn new things. Thanks.
This is a typical behavior for northern climates. Here in California I see a significant difference in bloom time between apricot varieties. For example, last year, bloom started Feb 14 on Gold Kist and Mar 11 on Afghanistan (25 days later).
This is probably as much variance as you can get (at least for stone fruit). Taking into account practical limitations (not all rootstocks are widely available, some are not suitable for your soil, some produce trees of undesirable size, etc.), you can probably get 3-5 days difference in bloom times at most.
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My project last year was to propagate some red mulberries that were growing in my woods and bring them out into the open. I successfully grafted one scion to an alba rootstock and airlayered two branches that are now also planted out. The grafted red mulb on the alba rootstock has swelling buds while the airlayers are still sitting dormant as are the original tree. But the the other alba rootstocks are still dormant. Although they are all in close proximity to each other the locations are a bit different. Looking at my other mulbs the Shangri La is swelling but the IE does not seem to be waking yet.
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That is interesting that your grafted Red Mulberry is budding, while while your airlayers and alba rootstock are not. Let me know when your IE wakes up…Here in North Florida, IE and Silk Hope wake up at least ten days after pure Red Mulberries.
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Alba rootstock
Grafted red
Air layered reds
IE
Shangri La
And I didn’t cross the red mud river to check on the reds in the woods!
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I assume your IE is still sleeping.
Your Shangri La should have woken up much earlier…unless you’ve had a long stretch of cool weather, dipping to freezing at night, until the last couple weeks (most mulberries need at least two weeks of temperatures that don’t reach freezing before they even consider waking).
IE still asleep. Looks like the airlayered reds are swelling but no green yet. Our forecast is straight spring but you never know. If we do get some weather that Shangri La is toast. The Alba’s are greening. The buds are so small on them. Do they tend to dwarf when used as a rootstock? They were just sold as Russian alba. 39 is the lowest projected low for the next 15 days and that takes us into the last average frost date. I even have one jujube that is showing some signs of growth.