Issue: September 2, 1996

Mimosa vascular wilt

Question: My mimosa trees are beginning to die. They were just getting large enough to make some shade. What is wrong and what can I do? The County Extension Agent collected samples and sent them to Las Cruces for diagnosis.

Answer: Dr. Natalie Goldberg, Extension Plant Pathologist, diagnosed the problem as Mimosa Vascular Wilt disease. According to Dr. Goldberg, Mimosa Vascular Wilt is due to a fungus, Fusarium oxysporum f. sp. perniciosum. It is a soil-borne fungus which invades trees through the root system through wounds or directly into weakened trees. Trees may be weakened by compacted soil or construction damage. Root injury during planting into contaminated soil can also result in infection.

This disease has caused considerable damage to mimosas in the southeastern U.S. It has entered New Mexico in contaminated soil in nursery containers.

Symptoms of this disease include chlorosis (leaf yellowing), leaf wilt occurring in early to mid-summer, and death of branches and the tree.

Balanced fertilizers (those with equal percentages of nutrients) may help alleviate symptoms in infected trees. High nitrogen fertilizers are not recommended. Water frequently to moderate wilt symptoms, but don't overwater and cause root rots. Dead branches should be removed and burned.

Fungicides provide little benefit. Use of resistant trees is the best means of avoiding the problem. Some resistant trees to consider include redbud, honey locust, and locust.

For more detailed information contact your County Extension Office and request a copy of Guide H-160, Mimosa Vascular Wilt (also available online).