Funny how the world works. There are many mulberry trees in Benicia., grown as ornamental specimen trees.. As far as I know, there are no silkworms farmed in Solano County now. But they used to be raised in Vallejo, at the Good Templars Orphans Home in the 1870s, where they were fed mulberry leaves. An ancient mulberry tree can still be seen in the lawn at the southeast corner of El Camino Real and Camino Alto.
A few weeks ago I had a query about mulberry trees from a woman who recently moved to our area. Her neighbors have been telling her to trim off all the skinny branches on her mulberry tree. She was unsure of what to do. So she made the effort to stop at the Master Gardener booth at the Benicia Farmers' Market.
You might have noticed these strange looking trees, almost obscene in their stumpy limbs. You might even have one on your lawn. The shape is most apparent in the winter, when the leaves (and branches) are gone. The leaves have fallen, but the branches have been removed. What remains are limbs with strange swellings at the ends, kind of like amputations. Those are pollarded mulberry trees.
Pollarding the mulberry is a practice that has its origins in the Old World. It provides new growth (leaves, branches) for the silkworm larvae to feed on. Here in California, the mulberry is now used as an ornamental. It is pollarded due to ignorance (i.e. everyone does it, but no-one knows why - it's just the 'done thing'.) The swellings (knuckles) on the end of the branches are storage for carbohydrates and nutrients that would normally be found in the tree roots.
IF you have a pollarded mulberry and would like to grow out the branches, it may not be a good idea. All those long, new whippy branches will not grow into strong scaffolding providing the tree with its original shape. They are poorly attached to the knuckles, and as they get older and heavier they will break off, which could be dangerous. Even if you leave just one to grow per branch, each of these new branches will be weakly attached, and may eventually break off. This is not a recommended option.
One thing pollarding does accomplish is keep the tree down to a manageable size. If you are considering planting a mulberry, think why you want it. Fruit? Look for a female tree. The male trees do not produce fruit, but they do produce lots of pollen, something to keep in mind if allergies are a problem. Shade? Black, red or white mulberry species can provide that. But they will grow from 30-5- feet high.. The white mulberry (Morus alba), also known as the silkworm mulberry , is the most common species. It is a fast-growing deciduous tree that can reach 30-50 feet in height. If you prefer something smaller, you may be better off with a weeping variety that does not produce fruit, such as Morus alba 'Chaparral.' There is also a medium-sized mulberry ( 25 feet high and 25 feet wide) called Contorted Mulberry (M. australis 'Unryu') with twisted, contorted branches that provide winter interest. All in all, there is no reason to pollard a mulberry unless you are cultivating silkworms.