Natural Herbicide Recipe for a Mulberry Tree

Here We go Round The Mulberry Bush

• There are three types of mulberry trees commonly found: white (Morus alba), red (Morus rubra) and black (Morus nigra). The name of the tree is not necessarily indicative of the mature fruit color. White mulberries may produce white, lavender, or black fruits. Red mulberries usually bear deep-red, almost black berries, while black mulberries, true to their name, produce berries of such a deep purple they appear black. Found in U.S. Department of Agriculture plant hardiness zones 4 through 10, mulberries grow wild in many forests and come to fruit from July through September. While it can be enjoyed for its ornamental nature or for its fruit, a badly placed mulberry can stain patios and surrounding accessories. Killing a mulberry isn't as easy as simply chopping it down, as the root system will continue to grow and fight for life, often causing a new tree to sprout in its place.

The Chemical-Free Fix

• Girdling requires no herbicide mixing and is one of the most efficient and natural ways to kill a tree. Girdling takes a long time to work, sometimes several growing seasons, but effectively kills the entire tree from root to top. Unlike cutting down a tree, girdling cuts of resources to the roots first. In early spring, use a saw or chisel to cut two rings around the entire trunk. Space them out about 1 foot apart. Dig in about 1-2 inches so that you pierce through the bark and reach into the phloem, the soft sticky area of the wood that moves nutrients through to the roots. The top of the tree may appear undamaged for some time since it is still able to suck nutrients upward, but underneath, the root system is beginning to die for lack of food. Remove any shoots that grow beneath the girdle since these will deliver food to the roots. In a few seasons, the tree should begin to show signs of stress signaling the beginning of its end.

A Direct Route to the Roots

• The basic concept behind a herbicide is simple, a tree reacts to what it eats the same way a human does. If you feed a tree poison, it will react with either sickness or death. Man-made chemicals are very popular because they work quickly and effectively, but some simple, natural items can be just as deadly when consumed in large amounts directly into the tree. To make the poison most potent, give it a direct route to the roots. Excavate the largest roots you see under the mulberry. Use an extra-long 1-inch drill bit to drill holes into the roots at about a 45 degree angle. Place several holes a few inches apart of each of the main roots.

Pick Your Poison

• Backfill the holes with a toxin of your choice, taking into account that these substances will act as a herbicide not only to the tree, but possibly to other plants growing in the vicinity. Used in large quantities, rock salt robs the tree of moisture and causes it to dry out. While you can certainly use common kitchen salt, which as the same chemical makeup, rock salt is preferable because its larger crystals keep it from disintegrating quickly. Another natural toxin is copper sulfate, which can be easily purchased at most home improvement stores. Copper sulfate causes reactions in trees similar to, but more potent than, salt. After filling the holes, water the area. You should begin to see signs of stress in as little as two weeks. If it has been several months and you see no progress, you may need to repeat the application of salt or copper sulfate. With patience and proper monitoring, the tree can die within a growing season.