Fruiting or fruitless, 6-foot dwarf varieties or 50-foot species and sun-lover or partial shade-lover, mulberry trees (Morus spp) of all types have complications of one sort or another. That said, the deciduous trees also have their benefits, providing yellow fall color, ample shade in warm weather, interesting shapes, tasty fruit and rapid growth. Choose a variety that suits your garden style and your ability to rise to the challenges the trees present.
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No mulberry varieties have highly toxic components, but some dangers exist in some varieties:
- Toxic sap on white mulberries (Morus alba) and red mulberries (Morus ruba), which both grow in U.S. Department of Agriculture plant hardiness zones 4 though 8, can irritate skin if you come into contact with the sap while pruning. Wear gloves and long sleeves to avoid problems.
- Unripe fruit of red and white mulberries is mildly toxic, causing hallucinations and digestive problems, so eat only the darkest fruit.
- All mulberries produce lots of pollen and debris, which can cause allergic reactions in some people.
Healthy trees resist both disease and pests better than trees that struggle to survive. Prune the mulberry tree to increase air circulation, water at the base of the tree instead of overhead, and remove diseased or dead limbs and leaves from the tree and surrounding soil to prevent recurring infections. Sterilize tools with rubbing alcohol so they don't spread disease.
A mulberry tree might suffer from one or more of these diseases:
- Armillaria root rot, commonly called Texas root rot, affects all mulberries to one degree or another, first causing discolored and dropped leaves, then killing branches and entire trees. Prevent the disease by keeping the tree healthy and by planting resistant varieties, such as a fruitless white mulberry.
- Bacterial blight causes black or brown spots on leaves, diseased growths on branches, oozing twigs or growths on the flowers, fruit and stems. Practice good tree care to help the tree resist blight.
- Canker disease, which turns leaves yellow or brown and causes dead spots on tree trunks, can kill a mulberry tree. Maintaining a healthy environment for the tree is your only defense for canker disease.
Unfortunately, even in the most healthy environment, insects plague mulberry trees. Here are some that might cause damage:
- Caterpillars form canopies in the branches of mulberries and feed on leaves and stems, sometimes destroying whole trees in the process. Remove any caterpillar nests you can reach -- they are easy to see -- and dispose of the leaves and branches.
- Scales suck the moisture from leaves and kill them. Apply sticky tape around the trunks of young trees to trap scales. Mulberry trees are too large to spray, so keep them healthy to provide the best protection.
- Like scales, whiteflies suck moisture from leaves, but they also deposit a sticky honeydew that causes leaves to turn yellow or die. Minimize whitefly invasions by strictly maintaining a healthy growing environment for the tree.
Mulberries create a mess in a number of ways:
- Black mulberry (Morus nigra), which grows in USDA zones 5 through 9, produces an abundance of dark fruit, which creates a cleanup dilemma with both dropping fruit and bird droppings.
- Black, red and white mulberries all have weak wood, which causes branches to break easily.
White mulberry is an invasive species in some parts of the United States, especially the Midwest and Northeast, crowding out native species.