Mimosa Problem

From your description, we do not believe this is Mimosa wilt, but have provided a couple of online resources for more information. Albizias do best in well-draining soil, regular water, especially when young, a layer of mulch and feed with a slow release or organic fertilizer formulated for trees. Here are some more specific tips, but suggest you contact a horticulturist at your local garden center familiar with mimosa trees to confirm that this is not a disease but tip burn resulting from irregular water:
1. Apply a 3 inch layer of mulch out to the dripline of the tree allowing 2-4 inch space around the base of the tree
2 Needs 5-inch depth of water during first summer planted and then decrease to watering down to depth of 1 inch every 7-10 days except during rainy weather
3 Check for signs of pest infestation or disease periodically looking for wilted growth, galls on trunk or slowing growth
4 If an arborist or horticulturist familiar with Albizias confirms it is Mimosa wilt, you may have to destroy it based on their recommendation

Fusarium Wilt of Mimosa (Albizia julibrissin) - Home ...
pubs.ext.vt.edu/2811/2811-1020/2811-1020.html
May 1, 2009 - Fusarium wilt is a common and lethal disease of mimosa (Albizia julibrissin)1, also commonly known as silktree. In the United States this ...
NMSU: Mimosa Vascular Wilt
aces.nmsu.edu/pubs/_h/h-160.html
New Mexico State University
Mimosa wilt is the most serious disease of landscape mimosa trees. The disease has spread rapidly throughout the Southeast and is limiting the usefulness of ...