Albizia julibrissin, or the mimosa tree, is commonly called the silk tree. This rapidly growing tree is native to China and was brought to the United States in 1745 as an ornamental species. Today, its popularity is attributed to fragrant pink pom-pom flowers. A mature tree can reach a height of 20 to 40 feet. The silk tree is considered an invasive plant in many areas because of its adaptability to numerous soil types, the fact that it re-sprouts when cut back and that it is spread by seed. It is easy to grow and requires minimal maintenance. The mimosa is susceptible to fusarium wilt (a vascular disease).
The mimosa tree has clusters of shimmering, hot pink, fragrant flowers that blossom in the spring. The silk-like flowers are what have gives it the name "silk tree," as the flowers appear to glisten like silk in the sunlight. Mimosa can be grown in full sun or partial shade, and they grow well in all types of soil. This tropical looking tree is also drought tolerant--making it an easy tree to grow. Be sure to allow enough space when planting as a mature silk tree can reach a width of from 10 to 20 feet. Mimosa are hardy in zones 6 through 9.
One mimosa tree produces up to 200,000 seeds in a year. This type of seed production is a threat to native species. The tree grows rapidly and can adapt to any soil conditions, making it an ecological threat. Animals and water disperse the seeds of the silk tree. The seedpods are able to float downstream via streams, creeks and rivers. The Southeast Exotic Pest Plant Council's Invasive Plant Manual management recommendations are through both mechanical, biological and herbicidal controls.
This tree requires little care because it is fast growing, hardy and adapts well to soil and possible drought conditions. It will require pruning to keep it within the bounds of its space in your landscape design. Pruning should be done after the tree blossoms. Cleanup can become a problem as the spent flowers and seed pods can be messy.
Fusarium wilt is caused by a fungus known as, "Fusarium oxysporum formaspecialis perniciosum"--the mimosa tree is susceptible to this vascular disease. The fungus clogs the vascular system tissue and interferes with sap movement. If the tree is attacked by fusarium wilt, the tree dies rapidly. Symptoms of this disease go unnoticed. The only way that you might see early symptoms of fusarium wilt will be if you happen to cut a branch of the tree and notice brown streaking that appears on the interior of the branch.
Once brown streaking of the vascular system tissue occurs, the tree will show some noticeable symptoms. You will begin to see yellow, stunted, wilted leaves. Fusarium wilt attacks the tree in early to mid-summer and as the disease progresses the branches that showed the yellow/wilted leaves will loose all of their leaves. This process continues as the fusarium wilt spreads throughout the entire tree. The bark will also be affected as the disease spreads. It will begin to crack, and you might see a white liquid oozing from the cracks in the bark--the white liquid will have a fermented odor.
Controlling Fusarium Wilt
There is no known means of controlling this disease, and the fungus can be present in the soil for up to two years. So, if you are going to plant another tree in that same spot you must choose one that is not susceptible to fusarium wilt. There are some Mimosa cultivars that are not susceptible to this disease including Charlotte, Tryon and Union.