Experts tackle readers’ garden questions.
Q: Last year, we cut down a fruitless mulberry whose roots were creating havoc with our cement driveway. We rototilled and cut out the tree roots, or as many as we could, and made a small garden. This spring, a plant started growing there and is now quite large. The leaves do not look like the tree we took out, and the “stem” is kind of speckled green, not like a tree trunk. Can you tell us what it is?
Mary Lou McNeill, Sacramento
Master gardener Linda O’Connell: Fruitless mulberry trees (Morus alba) grow well in a variety of soil types. They do well in climates with long, hot summers and can withstand air pollution. They are fast-growing trees and can reach up to 35 feet tall in three years. However, they form many large surface roots, making it difficult to garden under and around them. The surface roots also cause problems to walkways and driveways near the tree.
From a photo you provided, it appears that your new plant is a young fruitless mulberry, growing from the remaining roots. The leaves may not look like the ones on the tree you removed for a couple of reasons. Although not common with fruitless mulberry, some trees are grafted onto root stock, so any plant growing directly from the roots may not look like the grafted plant. Also, mulberry trees can have leaves of variable form, size and shape on the same tree, so you may be seeing leaves that you never noticed on the tree you removed.
You can remove shoots as they appear, but the roots will continue to put out more shoots. The only way to eliminate the shoots from coming into your garden is to completely manually remove or kill the roots. Post-emergence herbicides can be used. Take extra care to keep the material from contacting desirable plants. Follow label mixing and application instructions carefully.
Additional information on removing unwanted woody plants is available in the Woody Weed Invaders pest notes at the University of California’s Integrated Pest Management website, http://ipm.ucanr.edu.
Linda O’Connell is a UC Cooperative Extension master gardener with Sacramento County.
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