Here’s a new thread for those interested in reading / discussing scientific studies of fruiting mulberries.
I became interested in this topic about 2 years ago when it became apparent there are many sellers offering plants mislabeled in species and/or cultivar. As a result I decided to narrow down genetic tests to ID species and develop markers to build a library of genetic cultivar IDs.
It turns out that in India the mulberry is an important host for the silkworm and much work has been done that I can leverage towards my goals. In particular is the 2016 study of Mathi Thumilan et al which produced 206 primer sequences suitable for markers that are applicable to Morus, including subsets that are also applicable to other Moraceae species including Jackfruit and edible Fig.
Relationships among specimens in study of Mathi Thumilan et al.
In addition to genetic markers there is also a simple cytology ploidy test that can differentiate some of the mulberry species, in particular Morus nigra. Here are the details:
Species Ploidy
M. notabilis: 2n=1x=14
M. alba, australis, rubra: 2n=2x=28
M. macroura: 2n=4x=56
M. nigra: 2n=22x=308
I have gathered about 30 specimens for testing later on this year. If there are others you’d like to see added to the list, please advise where I can obtain a rooted specimen, commercially or otherwise. Thanks!
@GregBramblewood
I will contract a qualified lab for the biochemistry. At the moment I have a similar project with figs underway so the mulberries are a year or two off.
I might request a male or two from the USDA, but I am planning some experiments to create “feminized” seed. Perhaps you are familiar with this process, it is used extensively in cannabis, which is another dioecious species where you only want females for production. In short, you use an ethylene inhibitor to trigger floral meristems to become male instead of female and the seed produced with that pollen that is 100% female. This has the big advantage of being able to know the fruit phenotype of the “male”. If it works you could cross for example Kokuso with Illinois Everbearing, so it could be very cool. Will take some time! It will be a few years before I have enough stock material to really experiment, but maybe I will get lucky!
@GregBramblewood
To obtain viable seed, you will first need males. The plants sold for fruit from U.S. suppliers are female – although there are a few suppliers of seedlings. Those seedlings have come about from females having been fertilized by local M. rubra males or their feral hybrid males. I’ve yet to track down any purebred M. alba males in the U.S. In fact the USDA is having trouble tracking down purebred M. rubra males - due to the vast plantings of silk mulberries in a failed attempt to establish a silk industry here in the U.S. a century ago.
I see now I didn’t look at the USDA carefully enough, you are correct there are not any listed M. alba males. Seedlings will be the only source of true males.
I can understand that mentioning any techniques from cannabis can make hairs on the back of neck stand up; there is definitely a mixed bag of out there. That said, I feel I should mention I have a PhD in Botany, and work professionally as a plant breeder, and I think that the feminization technique has a reasonably good chance at working in mulberries, and other dioecious fruit trees, and would be a huge help in breeding with them.
I believe you’ll need to source them from the eastern hemisphere. F. Baloch and B. Tanyolac are leading Moraceae agricultural researchers in Turkey, likewise S. Sreeman in India and H. Ikegami in Japan.
Just finished transplanting these Persian and White Persian mulberries received bareroot several days ago from One Green World. They’ll now remain outdoors year-round with the others in our repository.
Today I placed the Trader Mulberries in Stuewe CP512 tree pots, plus did a little pruning and staking. Afterwards I fed them water-soluble 21-7-7 w/ micros at a rate of 1 level tablespoon per 5 gallons of water. Of that they probably received 1.5 quarts – the rest was used on other plants in our indoor shelter.
@GregBramblewood I suspect Morus alba cv. ‘Tehama’ may be useful to you since it is female once mature, but produces mostly male catkins when young. It is a pale near white fruiting type with good berry size and sweetness, but should probably be crossed with more acidic varieties to select for flavor balance.
Purebred alba are the rule in many areas where rubra doesn’t naturally range, and where those ranges overlap, significant energy is being put toward removing and controlling albas as they are reputed to genetically “swamp” the rubra. Here in northern New England, and surely in the upper Midwest, particularly urban and disturbed areas, albas are common enough and there are no rubras. I believe it was Lee Reich who contends that albas are the 2nd most common weed tree in NYC behind Ailanthus, which itself is about as much of a botanical juggernaut as the world has seen. Up there with Kudzu, Japanese knotweed, etc. I’ve spent a couple of weekends collecting specimens out of the sidewalk cracks and anywhere else with enough mineral soil to germinate the seeds (of mulberry that is, not Ailanthus)
@hobilus
Locations of naturally occurring M. rubra can be found in (1) USDA GRIN accession records, and (2) USDA digitized publications dating back to its inception.
Sounds like you meant to write that you haven’t found any pure rubra males. I happen to know that there is a small population of uniquely dwarf pure rubras found in western Massachusetts and far southern Vermont. Somewhat curiously, they’re confined to rocky exposed uplands- not quite what you’d expect of a floodplain tree. The species is listed on the Threatened/Endangered list for both states, so info is scant, but may be one of the few cases of rubras isolated enough to be pure. I found what little info I have by poking around and have some sites I plan to visit to verify and perhaps collect some cuttings at some point. It would be curious to know what drives the difference in phenotype, I.e. purely conditions/site dependent, or are they genetically unique. One would also think they’d need some adaptation to high light regime, which id counter to the conventional wisdom on rubra.
The cultivar “Kokuso” was reclassified as an M. alba phenotype a decade or so ago. If true it is a good candidate for distinguishing alba from rubra. The U.S. nursery stock originates from S. Korea.
