Morus alba – Mulberry

(Photo LOF - morus alba var Badena Tut)

Morus alba – Mulberry : article et photos [grand format] paru dans Fruit Gardener, revue des CFRG

The propagation of morus alba or mulberry trees can be attributed to silk farming in the Near East during the period of expansion of Islam. The leaves served as feed for silk worms. Based on research published in the past decade, mulberry leaves and fruit contain a wide range of carbohydrates, polyphenols, phenoloxdase and micro-nutrients.¹  
Pakistan continues to use forage varieties that remain the best feed for silk worms.² 
The antibiotic properties of morus alba leaves are also used as a cataplasm in traditional local medicine and in liver, kidney and other medications.
The high price of silk sustained a long-term market for mulberry leaves on the Iberian peninsula. 
Its value as a feed source overshadowed for decades the quality of its fruit, despite being well documented in ancient Chinese medicine, its red berries serving as a blood fortifier.

(Photo LOF - morus alba var Emmanuelle)

An excellent fruit tree in our climate
Morus alba can be found in a wide range of climates from hardiness zone USDA 4 to 10a.
It produces quality fruit only in zones 8 and higher, the milder the spring, the earlier and sweeter the berries. In zones  9 and 10, the earliest varieties can be harvested in April, near the end of the citrus harvest when there is little fresh fruit available other than loquats.
In the countries of Central Asia (Afghanistan, Pakistan, Azerbaijan, Armenia), its fruit has been a major source of sugar since the Middle Ages, having a sugar content up to 18%. Frenchman Pierre Meynadier (1900-1985) ³ methodically collected morus alba from 1965 to 1983 in countries that have identified and cultivated fruit varieties: USA, Canada, United Kingdom, Ireland, Australia, New Zealand, Rhodesia, South Africa, Syria, Lebanon, Israel, Iran, Iraq, Afghanistan, Russia, Rumania, USSR countries of Central Asia, etc. The same varieties often changed names as they migrated countries, but morus alba has considerable chromosomal variability and a tendency toward instability.⁴
As a result there are numerous varieties; here in Portugal, we have some 20 very distinct cultivars.
French nurseryman Frederic Cochet ⁵ offers 16 varieties of morus alba fruit trees with white, pink, purple and black fruit. We have planted about a dozen of his varieties.

The fruit of the morus alba has peduncles.
The best edible fruit is the Pakistan variety from Islamabad. It has  a 2‑inch long purple fruit which we prefer when it is not quite fully ripe; when it has a slightly firm skin with the perfect sweet-sour balance. At full maturity, the fruit falls easily from the tree and loses its texture.
Many of the varieties with white fruit are very sweet and don’t stain.
These are the ones that we dry or make into syrups.
Dried mulberry powder is used as sugar in Pakistan, the Guzziola Hort in Steud cultivar being especially sweet.
Dried mulberry tastes somewhat like molasses; it is a tasty dried fruit with a texture similar to Turkish nougat, crunchy and spongy.
Like dates, it is rich in minerals.
We consider the pink Emmanuel mulberry the best for fruit salads especially mixed with wild strawberries.

(Photo LOF - morus alba var Pakistan)

Irrigation of morus alba
Two failures of our drip irrigation system revealed that a lack of water caused the premature yellowing and dropping of the tree’s leaves without killing the tree or disturbing its fruit production the following year. The same variety of tree next to it ended up in a very wet, non-draining area (heavy clay soil) as a result of a leak in the underground waterline.
It developed abundant, very green foliage, bending its branches toward the ground, but failed to produce any fruit. Fortunately, our other morus alba were properly irrigated.
This confirms that using morus alba for forage requires a great deal of water, which is why they are planted in valleys or along riverbanks in Asia and the Andalusia.
However, for fruit production, water is necessary but not in excess.
In the Alentejo region of Portugal, we give 40 gallons/week for a 5‑year old tree and 80 gallons for adult trees).


(Photo LOF - morus alba var Pakistan / fruit)

Size of mulberry trees
Instructions frequently say not to prune mulberry trees except during the winter and then only slightly. This is not the case in our climate where the tree is vigorous and lives for hundreds of years.
All silk farming manuals call for the removal of most of the leaves from branches, except for the end buds. Ibn al Awwam (a 12^th century Sevillian agronomist) suggests that a mulberry tree can be revitalized by cutting its trunk off at a height of about five feet and then keeping the most vigorous shoots.
We trim our trees back quite severely after the leaves have fallen. When young, these fruit trees should not be allowed to develop a single trunk but rather to spread out.
We then cut them straight across the top in spring in order to cover them with nets. If we don’t do this, they continue to grow upwards and the birds steal all of the berries.
In Portugal the trees are planted close to chicken coops because chickens love mulberries! Insects and wasps – great sugar lovers – are also fans!
Fine mesh nets that allow the wind to blow through are used to completely cover the trees. Large quantities of fruit are harvested by simply shaking the branches and letting the berries fall to the into the nets.

(Photo LOF - morus alba / fruits)

The future of Mulberry trees
We are great fans of these large, beautiful trees that have such a remarkable ability to adapt to poor soils. They grow quickly and produce abundant fruit. Morus alba is cited some 600 times a year in abstracts of scientific publications and patents. Less than 25% of these citations relate directly to the fruit, most referring to the use of the leaf .⁶ Research relating to the fruit is focused mainly on cardiovascular medicine where tests on rats with hypercholesterolemia are positive.⁷
Recent Chinese studies indicate that the antioxidant benefits of mulberries vary significantly depending on the variety and the maturity of the fruit but have identified certain promising varieties for consumption as fruit and fruit juice.⁸
Chinese enologists have shown that dark fruit from morus alba trees are an excellent source of anthocyanin, which can easily be extracted on a commercial basis.⁹
The mulberry tree has a bright future – it has good varietal options, its best fruit varieties are easy to grow and its fruit is excellent.

(Photo LOF - morus alba / dried fruit)

¹ Four years ago Peshawar University published a comparative study (http://www.jcsp.org.pk/index.php/jcsp/article/viewFile/1123/722) classifying the mulberry by its content of chromium (Cr), nickel (Ni), and zinc (Zn).
² (http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5967.2011.00316.x/full
³ (http://www.coplfr.org/articles33a38/article33pag1.html
⁴ Demonstrated by the Central Sericultural Research and Training Institute of Berhampore: http://cat.inist.fr/?aModele=afficheN&cpsidt=2331160).
⁵ (http://www.cochetfrederic.com/muriers-a-fruits.html)
⁶ Leaf production without herbicides is possible with irrigation: http://epubs.icar.org.in/ejournal/index.php/IJAgS/article/view/2754
⁷ (http://www.worldscinet.com/ajcm/39/3901/SO192415X11008634.html).
⁸ http://www.informaworld.com/smpp/content~db=all~content=a931471196
⁹ http://journals.uzpi.cz/publicFiles/39923.pdf