Fruitless mulberry

Botanical name

Morus alba (fruitless, male selections)

Type

Fast-growing deciduous shade tree from China

Size

30 to 50 feet tall, dense and round-topped (Utah State University)

Hardiness

Zones 5 to 9; zones 6b to 7b here

Where it is found

Older yards and street strips on the valley floors, about 4,000 to 5,100 feet

Known weak points

Soft, weak wood, wide shallow roots, ice damage, low shade tolerance

The tree known as fruitless mulberry is a male selection of white mulberry, Morus alba, which is why it does not stain the sidewalk with berries. This page covers how to identify it, where it grows in our elevation bands, the damage we read about for it and when pruning, cabling or removal is the right call.

How do you identify a fruitless mulberry?

The leaves are alternate, glossy, dark green and two to four inches long, with a coarsely toothed edge that ranges from plain to deeply lobed, often on the same tree. Break a stalk and milky sap appears, the USDA Forest Service notes. The crown is dense, round and low-branching.

The bark is thin and shallowly furrowed. In a fruitless tree there are no berries; Utah State University says male trees are fruitless and generally preferred, and birds love the fruit of the female.

• Glossy leaves, some lobed and some not, on the same tree
• Milky sap when a stalk breaks
• Dense round crown
• No fruit on the male selections

Where does it grow in Reno, Carson City and the Carson Valley?

It is a valley-floor tree. Utah State University rates it for zones 5 to 9 and high for drought, salt, poor drainage and alkalinity, a profile that matches Reno (4,505 feet, zone 7b), Carson City (4,680 feet, zone 7a) and Dayton (4,384 feet, zone 7a). Minden is zone 6b and still inside the range.

Higher up, where Incline Village is at 6,437 feet and zone 6b, the species sits near the cold edge of its range and the Tahoe lot trees are conifers. Fernley (4,154 feet) and Fallon (3,965 feet) are zone 7a and sit in the warm part of the range.

What goes wrong with it here?

USU calls it weak as a street tree with soft, weak wood that tends to warp. Limbs can break in wind, ice and wet snow. Look at storm and snow-load breakage for how those failures happen.

The Forest Service describes a wide, spreading root system of a taproot and laterals, with most lateral roots in the upper one to three feet of soil. On a lot with a sidewalk, driveway or sewer line close to the trunk, that matters; see tree roots, sidewalks and sewer lines. Mulberry is also rated not good under power lines, and its low shade tolerance means a tree crowded by buildings or a bigger tree will thin.

Pruning, cabling or removal: which is the right call?

Dead wood and hanging limbs come off any time. Other pruning is best in late winter, when the tree is dormant. Because the wood is soft, a few clean cuts that lighten the long limbs do more good than a hard cutback; see why topping is not pruning.

Cabling and bracing can help a tree with a good trunk and one weak union. Removal is the usual answer where the trunk or roots are decayed, a major limb has split from the main stem over a house, or roots are damaging a driveway and sewer line. Stump grinding follows removal. For firewood, call the office for availability and pricing.

What does Battle Born Tree Service do about a mulberry?

We look at the whole tree, not only the part that worries you, and the free estimate lays out pruning, cabling or removal. The crew is eight people, two of them ISA Certified Arborists, and the phone line is staffed seven days a week at 775.232.8243. We do not plant replacement trees.