Black Spots on Banana Leaves

A closeup of a healthy banana leaf

The name for the disease that produces ugly black spots on banana leaves originated in the land where the affliction was first noticed in 1963 -- the Sigatoka Valley of Fiji.

Identification

Black leaf streak, also known as black Sigatoka, is a fungal disease that attacks banana leaves across the globe. The symptoms initiate as small, black flecks that grow into dark red, brown or black lesions. They may occasionally take on a purple tinge, reports the University of Hawaii at Manoa.

Prevention/Solution

Black Sigatoka is brought on by the fungus Mycosphaerella fijiensis and moves from tree to tree via wind and rain. The disease is difficult to control, and while fungicides may be used, simple removal of diseased leaves and pruning of branches as a means of improving air circulation is commonly done to manage black leaf streak.

(Ref 2)

Considerations

No varieties of banana plant are resistant to this disease, although work is being done to develop hybrids less-susceptible to black Sigatoka. The University of Iowa Extension Service estimates that between 15 and 20 percent of the price of bananas is related to the cost of managing diseases like black leaf streak.

References

• University of Hawaii at Manoa: Banana Black Leaf Streak Disease in Hawaii - Symptoms and Integrated Management
• Iowa State University Extension: Banana - Black Sigatoka Disease