I often get questions this time of year about identifying a certain blooming tree. You may already know about this rather feathery leafed specimen that, similar to the honey locust tree, is covered with beautiful pom-pom pink to peach-colored blooms. It’s the mimosa (Albizia julibrissin rosea).
It seems that ladies especially love the look of this tree and want one in their landscapes. Hopefully, this profile will not only help you identify the tree, but keep you from making the mistake of planting one. Yikes ... did he just say DON'T plant one? Yep, I did.
This beautiful, blooming specimen is also known as a Persian silk tree or a pink siris. It’s beautiful in late spring and early summer, when covered in blooms, but the rest of the year it's either pathetic looking or overwhelmed with insects and disease. In Hawaii, the mimosa is considered a weed and often nicknamed the “Beautifully Awful Weed.” In Texas, it's vulnerable to borer insects which can girdle the cambium layer just inside the bark and kill the tree.
A big reason to avoid them is their susceptibility to the mimosa webworm, a pest that’s also highly destructive to honey locust trees. When fully grown, the larvae are about a half-inch long and gray-brown or pinkish with five narrow white longitudinal stripes. They spin webs around flowers and leaves and feed on the foliage within the protection of the web. The webbed leaves become skeletonized, turn brown and die.
Then there's mimosa wilt, a fungal disease (below).
The classic symptoms are wilting and yellowing foliage. In some cases, the leaves become dry and shriveled while remaining green or yellowish for some time. Later, the leaves fall, and the branch dies. Usually the tree is affected branch-by-branch, and dies completely within a year of symptoms onset.
Another common characteristic of mimosa wilt is brown discoloration in the sapwood, especially the outermost annual ring. That’s caused by gum-filled tissue cells, which hinder or completely inhibit water movement from the roots up. The discoloration can be seen in trunks and branches even before the leaves wilt. Plus, during the summer months, it is not uncommon for the bark of infected trees to rupture and exude fermented, frothy sap which attracts many insects.
Since the fungus lives in the soil and enters the tree through the roots, dead and dying trees should be cut down and destroyed to prevent its spread.
Now … given all that … do you still want to plant one?
IMAGES: Closeup - Texas Invasive Species Institute; Wilt - Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org