The next steps in developing better cold hardy mulberries

Many are happy with illinois everbearing, and no doubt we can see why. I would like to improve the size and vigor of all cold hardy mulberry and make them as prolific as possible. First we have to find those that are cold hardy to 10 degrees and colder. Many mulberries in warmer clients get 3" + in length which is more than 2x to 3x the size of our best mulberries. One way to improve them is buy 10 degree hardy large fruiting types and plant thousands of seeds. One will eventually be a male that survives very cold temperatures. It might takes several generations.

See these topics

I have 30 females and 7 males now that are improved types. I have 100 regular mulberries

This is the first improved type i’m making available for free.

10 Likes

Has anyone done anything to improve Rubra without foreign germplasm?

2 Likes

@dannytoro1

Nobody is really doing anything right now. Most crosses were made by accident. The only reason mulberries are here at all is because people wanted to turn the usa into a silk producing country. That venture failed because the silk worms didn’t make enough profits in most places here.

The fines for not growing at least 10 mulberries was hefty

https://history.textiles.ncsu.edu/textile-industry-history/silk-in-america/

Here is the history of silk.in the USA

" Skip to main content

NC State Home

Textiles History

Silk in America

The story of the silk industry in America dates to the earliest English settlers in Virginia. James I tried to compel Virginia tobacco planters to stop cultivating tobacco, plant mulberry trees and sustain silk worms to supply raw silk to English factories. As early as 1623, he decreed that a planter would be fined £10 if he did not cultivate at least ten mulberry trees for every 100 acres of his plantation. Bounties were extended in 1657: 10,000 pounds of tobacco for every £200 worth of silk or cocoons in a single year. The bounty was extended, dropped, extended again and abandoned. No one wanted to “farm” silk when they could grow tobacco. Silk was too labor-intensive.

Silk culture was tried again in Georgia in 1732. In 1759, 10,000 pounds of cocoons were received at the processor or filature in Savannah, but eventually silk culture gave way to cotton. Chalk up another failure for silk cultivation.

South Carolina was the next colony to attempt the raising of the mulberry tree and silk culture. In 1755, a Mrs. Pinckney carried with her to England, enough silk of her own raising to weave three dresses, one of which was presented to the Princess Dowager of Wales. Never the less, silk from South Carolina was very much a novelty. Strike three for silk culture in the South.

In New England, Governor Leete, of Connecticut who died in 1683, had raised silk and had a suit made from this silk. The mulberry was mentioned in legislation in Connecticut in 1732. Dr. N. Aspinwall sent trees to New Haven and Mansfield, along with the eggs of the silkworm, in 1762. The Connecticut Assembly offered a bounty for mulberry trees planted and another cash bounty for silk produced. Cultivation increased. Dr. Stiles, the president of Yale, grew silk from 1758 to 1790. A woman and three children could make ten pounds of raw silk worth $50 in five weeks. Silk processing was spreading throughout the state. As late as 1810 the three chief silk counties produced $28,5000 worth of raw and sewing silk, plus half of that value in waste silk for spinning.

Dr. Aspinwall also introduced silk culture into Pennsylvania in 1767 or 1768. A filature was built in Philadelphia about 1770.

In the early decades of the 19th century, silk culture continued to entice investment. No one hit it big but people kept trying. There was tremendous speculation in the 1830s. A new variety of mulberry was introduced from China by way of the Philippines, then France and into Baltimore. Gideon B. Smith planted the first trees there in 1826. Growth was more rapid and the leaved were several times larger. When news spread, nurserymen were inundated. The demand soon exceeded supply and a wild rush took place.

Copied from The Story of Silk and Cheney Silk. Image courtesy of Peter Metzke.

Several of the Cheney brothers of South Manchester, Connecticut began experimenting with sericulture around 1833. The first nursery was established in South Manchester, Connecticut. Records of the time show that moris multicaulis , seedlings of the new species, sold for about $4 a hundred in 1834 rose to $10 in 1835 and to $30 a hundred seedlings in 1836. A shipment from Marseilles arrived in April 1836. Only 15,000 of the original 70,000 shipped survived. No more would arrive until the autumn. The Cheney brothers planted in May and the shoots shot forth in great abundance. Some 6,000 silkworms were fed beginning in June and yielded three bushels of cocoons. The boom was on. In November 1836, the Cheney brothers leased land in Burlington, New Jersey, and started a nursery and cocoonery. Another was started in Cincinnati, Ohio. 1837 was a bountiful year. The Cheney brothers sold about $14,000 worth of trees from Burlington and had about 50,000 on hand. A man from nearby Monmouth, New Jersey made a clean profit of $3,000 from a $400 investment. The rage continued unabated through the Panic of 1837 . Investment in silk was solid. By January 1839, the price of a mulberry tree ranged from a dollar to five dollars. At the same time it became apparent that the mulberry was not hardy enough to be raised in the North and hard times spread to silk. By 1840, the crash was complete. No one wanted the trees at any price. Importers could not even pay the freight on shipments from abroad. See also the page devoted to Nonotuck.

In 1844, a fatal blight affected almost all the trees in the country. Growers were driven out of business. Even in Mansfield, Connecticut, where it had been most prosperous, the culture was finally abandoned. Writing in 1916, Manchester said,” The fundamental reason for this is, not that mulberry trees and silkworms cannot, though with difficulty, be raised in this country, but that the production of raw silk (cocoons) is essentially a household and hand process, still requiring, as in the days of ancient China, infinite patience and an disproportionate amount of human labor. Even in Italy, during the silkworm season, the whole house including the bedrooms and beds, is given over to the worms, upon which the women lavish every attention from daylight until late at night, – and for all this trouble and work, they net only six or seven cents a day. In Japan and China such household labor may bring as low as two or three cents a day.”

“Silk cannot be grown by the highly paid labor of the United States in competition with such meagrely (sic) rewarded Oriental drudgery, nor can household hand labor compete here with other industries in which most of the energy is furnished by power and most of the work done by machinery.”

In Colonial days, whatever silk was manufactured here, was made entirely in the home. It was reeled by hand, thrown or twisted and doubled by hand, and woven on the crude foot-powered loom of that period by the women of the family. All early attempts in the 18th century at silk manufacture using the factory system were failures.

Rodney and Horatio Hanks began the first silk mill in the United States at Mansfield, Connecticut in 1810. The “mill” was only 12 ft by 12 ft in size. The mill made sewing thread by adding twist on machines of their design run by water power. The mill and two others associated with this venture were abandoned in 1828 because the machinery was too crude to produce commercial sewing thread. In 1815, William H. Horstmann, built a mill in Philadelphia for production of trimmings and ribbons. He imported a Jacquard loom in 1824. The Mansfield Silk Company, begun in the center of the silk growing district, made use of water power for reeling, but was unsuccessful in attempts at weaving. The mill failed as a result of failure in the speculation with the morus multicaulis .

The first really successful manufacturers in the United States were the Cheney Brothers. The original mill was begun as the Mt. Nebo Silk Mills, South Manchester, Connecticut, in January 1838. Although somewhat neglected during the time of the morus multicaulis speculation, it is the only mill established before that date that was permanently successful.

Silk also came to Paterson, New Jersey. With a powerful source of water provided by the Passaic River and the great waterfall, many silk manufacturers settled in. Paterson was also close to New York City which provided a steady stream of immigrant labor in the late 19th century. A survey of companies in Davison’s listed 28 pages of silk companies doing business in 1927. The nearby town of Passaic by contrast had few silk processors and concentrated on worsted wool instead. Production dwindled steadily as companies moved south and synthetics took over much of America’s needs. The number of companies doing business in Paterson declined to 7 1/2 pages in 1950.

View of the skein winding room in a silk mill in Paterson. Date posted 1906
Courtesy Bill Wornall Textile Postcard Collection

In 2012, American Silk Mills of Plains, Pennsylvania is one of the few survivors and traces its beginnings to the Gerli family in northern Italy. The company merged with Cheney Bros. in the 1970s.

Sources:

  1. Manchester, H. H., The Story of Silk and Cheney Silk , Cheney Brothers, South Manchester, Connecticut, 1916.
  2. Davison’s Textile Blue Book , 40th Annual July 1927. TS1312 D3 1927

Textiles HistoryHome

Connect With Us

© 2025 NC State University. All rights reserved."

5 Likes

@dannytoro1
The majority of untended mulberries in the USA are believed to be feral M. rubra x alba.

This is not true. M. rubra is native, and perhaps there are others.

6 Likes

I know of a tree that has mulberries slightly over a inch that has good flavor, though they are black.
Also found a Lavender fruited tree with good flavor that had massive berries, but it was on the edge of a corn field and had spray drift damage that may have caused the huge fruit.

It would also be appealing to me to breed the different flavors and colors of the local wild ones to have larger fruit too.

4 Likes

That’s normal. The names ‘rubra’ and ‘alba’ do not refer to fruit color.

1 Like

@KS_razerback

I’m planting some pure morus alba , morus nigra , and crossing back to rubus x alba. The crosses are highly fertile. Im planting 4 new illinois evernearing on their own roots non grafted. Then i will graft half a male true to illinois everbearing. Ant improved types you want me to try we can and vice versa. Since you are in Kansas if you want, i can always show you my males and females. You are welcome to hundreds of cuttings if you want them off of any of the breeding group.

3 Likes

To me the black fruited aren’t quite as special to me (although I still love eating them) because they are the most common.

1 Like

I’m concerned that you have fake M. nigra. The real species would not survive your winter.

1 Like

@Richard

M. Nigra i thought was zone 6 more or less? Im using it for breeding crosses @Richard and it has not overwintered yet. I’m growing seedling M. Nigra not the improved types.

2 Likes

I have a few of each of Illinois everbearing and Lawson dawson trees growing and I’m curious how they will compare to my favorite local wilds.
I also want to get a row of each of the best/most unique wild ones growing in a row, and maybe experiment on a couple pruning methods for mulberries.
How do you select your males? Do you count how many flowers are average on each panicle? (It seems like it might directly reflect how long the fruits will be based off how all the large fruited it has in its genetics, males from the large fruited improved types have extraordinarily long ones from the pictures I’ve seen) I might be Interested in some of your selection, after I get my initial collection of wilds going.

4 Likes

Yes. M. alba, M. macroura, M. nigra, and M. rubra each have black fruited specimens.

Zone 8. Also note the negative characteristics of M. nigra for breeding: it is very slow growing and hyperploid.

4 Likes

@KS_razerback

My males are from my cross of albaxrubra.

2 Likes

Any cross of nigra X either alba or rubra will result in very very strange polyploids… if the cross can even be made.

5 Likes

More likely alba x (rubra x alba).

3 Likes

I cleared the spots today and everything is ready to go for the new mulberries.

7 Likes

Are you growing any long fruited mulbs? I’m crossing M. macroura selections with rubras & hybrids in hope of creating a tree with both cold hardiness & jumbo fruits. By “cold hardy” I was only thinking zone 7 or 6, but you have to start somewhere.

Here’s one of the crosses I performed last Spring, & have a few seedlings growing now from:

I also would advise NOT using M. nigra for breeding purposes. It has well over 10x as many sets of chromosomes as any other species you’ll be using, AND it’s already been crossed with the long fruited species M. macroura before. The many sets of genes for tiny fruit always seem to overwhelm any of the inherited “long fruit genes”. Mark Travis (Livinginawe) wrote a snippet about it one attempt on his website: Hybrids | growingmulberry

11 Likes

What I would really like to see in mulberry breeding are more varieties along the lines of Gerardi with even better fruit. I would argue thatore vigor isn’t needed so much as a manageable size. I would say most home orchardist are not in a position to manage and harvest a full size mulberry tree. They can be kept smaller with pruning, but they can also get away from you quickly.

5 Likes

@jcguarneri

Yes, i agree with your goals being important. M Nigra is a natural dwarf. It does sound like my plan wont work long term. Everyone is cautioning M. Nigra will not be a good choice for me. I will still plant them out.

@DijonG

It sounds like our goals are similar. I not only want a long fruit, i want a fat fruit as well. If it is longer or bulkier is not important as long as i increase weight significantly.

2 Likes

@DijonG what variety is the father?

1 Like