Creeping Charlie: The sneaky weed taking over
Q. On May 10, you wrote on dichondra. That appears to be the weed I have throughout my yard and flower beds. It grows fast and all over. Fortunately, it has shallow roots, allowing it to be easily pulled up from our flower beds. It has small purple blossoms and points surrounding each leaf. Is this dichondra? If not, what, and can I treat it the same way? — L. Whiting, Hampton
A. The plant you have described is Glechoma hederacea, also known as Creeping Charlie or Creeping Jenny. This weed of the mint family is a herbaceous perennial that spreads both by seed and stolon (creeping stems). The plant was introduced from Europe with the expectation it would make a good ground cover. Leaves are bright green and round with scalloped edges (dichondra is smooth). The leaves are opposite one another on square stems that produce root at the node. It has a mint-like aromatic odor when it is crushed. The weed is sometimes confused with the winter annual henbit.
Recognizing that the weed has a preference for a moist shady spot provides a clue for control. Eliminate these conditions and you can discourage its growth. Maintaining a healthy, dense lawn will give your turf competitive edge over the invader. Postemergent products containing Triclopyr are effective. It is often found in combination with Dicamba, 2,4-D and Mecoprop. Applications are most effective in the fall when it is actively growing. Always read and follow label recommendations carefully.
Q. I removed a black walnut tree from the yard and would like to place a Chicago Hardy fig nearby. Would there be any issue with this? I’ve had difficulty finding a definitive answer. — M. Minor, Norfolk
A. As you know, members of the Juglandaceae, particularly your black walnut (Juglans nigra), produce the allelopathic chemical juglone. The chemical occurs naturally in all parts of the tree. While juglone is most highly concentrated in the soil within the dripline of the tree, the area beyond may also be toxic for sensitive species. Residual toxins may remain for some time in the soil after the tree is removed and as the roots decay.
It is interesting to note that the toxic effects of walnuts on other plant species have been observed and pondered for over 2,000 years. The ancient civilizations of Greece and Rome recognized its allelopathic effects. Juglone, the active ingredient, was not isolated and identified until the 1850s. And in 1921, M. T. Cook, working at the Virginia Agricultural Experimental Station, noted the negative effects of walnut trees on nearby tomato plants. Subsequent studies by numerous researchers documented the toxic effects of walnut on a whole host of agronomic crops.
Now, getting back to your fig. I reviewed several articles, and the consensus from multiple extension sources confirms that these toxins may remain in the soil for several years. The articles listed species that tolerate the toxin better than others, but I did not find fig among these. It seems reasonable that factors such as soil type and conditions, size of tree and the root system, and extent to which roots were removed play a role. Depending on these, and when your tree was removed, it may just be prudent to consider another spot for your Chicago Hardy.
Send questions to wkspen@gmail.com or to Home + Living c/o the Daily Press, 703 Mariners Row, Newport News, VA 23606.
Maintaining a healthy, dense lawn will give your turf competitive edge over the invader.