In an article I read many years ago, the author stated that Trifoliate orange rootsock can be used to delay early bud break in grafted citrus (so as to avoid late freezes). In practice I have not noticed a discernible difference between the same citrus cultivar on trifoliate vs other citrus rootstock.
So my question is: Does the selection of the rootstock have any effect on the onset of bud break…for mulberries?
I have been grafting most mulberry scions to a rootstock that ends its winter dormancy fairly early…because cuttings of it root at near 100% and the grafts generally take. Would it make any difference in bud break timing if I grafted to a rootstock that had a later bud break (such as M. alba tatarica or pure M. rubra)? Gaining a couple weeks of bud break delay could mean a huge difference because late freezes are so common in my neck of the woods.
Just my unsubstantiated guess. Trifoliate is deciduous while most other citrus are evergreen. that likely contributes to any bud break delays. That however does not translate to other species. We know root stock effects flavor, ripening time and fruit size. But since bud and flower formation easily happens on cut wood. I assume that rootstock that breaks dormancy early is more likely to push earlier bud break then it is to delay it, and a rootstock that breaks dormancy later will not effect the scion wood as it breaks independently of the roots. I would also assume that if a very early scion is grafted to a very late rootstock, the results might be susceptibility to late frost damage.
None of what I said does not make exploring the idea worth wild. As far as I know there are few to no cultivars of mulberry exclusive for rootstock. Once a few dwarf trees where identified growers just went with it. No real development. Now what you are going to want to do to reach your goal is get wild mulberries or seeds from the northern most parts of its range. If mulberry rootstock can delay bud break thats where your going to find it.
Thanks for the reply.
I have read that not watering dormant plants (in a dry climate) will delay bud break, so I’m guessing that if the rootstock can stay asleep (as with a very northern rootstock) that might be akin to simulating drought.
Simulating drought dormancy in mulberries is going to be hard. Once outside in the ground the tree will certainly have enough moisture on the east for all its spring needs. Despite our hot dry summers we do not have anything like the persistent dryness over winter the west coast has.
Haven’t read about mulberries specifically, but have read about it in regards to apples. The problem is actually coming across this info. It doesn’t seem like differences between rootstocks are extensively documented in the literature, outside of what is important to commercial growers (yield, disease resistance, precocity, size.)
Being that the info is rather spotty on apples (a huge cash crop) I imagine it is non-existent on mulberries.
My gut feeling is that the rootstock has very little to do with when bud break occurs. My reasoning is that if the selection of rootstock actually made much of a difference there would be more documentation available on the internet, since late hard freezes are such a common problem. I’ve “googled” with every combination of words I could think of… and didn’t find anything.
Seems to me that we see an awful lot of species-specific bloom, and the apricots all seem to bloom pretty much at the same time, as do pears, apples, and so on in their time. But they include so many different combinations of rootstock/cultivar you would expect them to be spread out a great deal if the roostock had a lot of influence. Granted, some cultivars are earlier/later than others in their species, but that’s trackable, I would think, by cultivar rather than by rootstock.
I’m not a scientist, nor do I pretend to be one, but going from memory, and consolidating what I’ve read into a coherent whole, I believe this is where we are with that research:
Rootstock can and does affect budbreak. So why don’t we all know about this? Here’s the problem: the effect is inconsistent.
It appears that when the plant breaks bud is a complex mix of not only the normal factors we would usually consider (like weather, sunlight, and variety) but also probably by an interaction between the individual variety of scion, the rootstock, and the “terroir” of the place where it is planted.
So the most that researchers could say would be something along the lines of, “At this specific location, Cortland apples on MM111 break bud 4 days after Cortland apples on M7, and we are confident that this difference is statistically significant (i.e. the effect is “real” and not just noise.)
However, this effect doesn’t necessarily transfer to another situation. Golden Delicious on the same rootstocks in the same location might break bud at exactly the same time. Gala on the same rootstocks might show a 2 day difference in bud break 3 states away.
TLDR: I think there is no argument (or there shouldn’t be) that rootstock can affect/change budbreak. However, since we can’t reliably predict what the change will be dependent on variety and location, it tends to be ignored.
Just a quick little peruse of the internet turns up an article that helps to corroborate what I’m saying, but it doesn’t deal directly with this question, more tangentially.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.572.8464&rep=rep1&type=pdf
I tend to get interested in something, read all the articles I can sufficient to educate myself on the topic, but unfortunately I don’t leave myself a trail of breadcrumbs about what I read and when. But that’s not a bad article that relates to the topic.
Again, let me just reiterate that I am a layman who has self-educated. I am fairly confident in what I have read and what I’m telling you, but I do not have the years of knowledge and experience of someone who is in this profession.
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.
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.
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.
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).
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
Great idea! I’ve never heard of anyone grafting an alba to a nigra…It should be an interesting beast!
OK! Proof positive (at least for plums).
just for kicks, haha
although a bit counter-intuitive from a gastronomical point of view 
Ha ha ha! My one mulberry tree is composed of many albas, rubras and nigras, sometimes all on one stem.
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.