Black Spots on Banana Plants

Healthy banana leaves are green.

Black spots on a banana plant (Musa x paradisiaca) indicate diseases, and there are four major diseases that exhibit this symptom. Gardeners should be able to clearly differentiate among the diseases, then provide treatment.

Diseases

Sigatoka, a type of leaf spot, and black sigatoka, or black leaf streak, causes banana plants to develop black spots. Two other diseases -- black-end and cigar-tip rot -- make the banana fruits turn blackish.

Considerations

If your bananas are black, you've got either black-end or cigar-tip rot: cigar-tip rot affects banana flowers first and then extends to the fruits. Plants with sigatoka develop small purple-black spots that grow larger over time. Those with sigatoka leaf streak have longer, line-like lesions.

Treatment

Sigatoka responds to fungicides and orchard mineral oil, but sigatoka leaf streak responds only partially to fungicidal treatment; many growers lost crops affected with this disease. Gardeners can prevent fruit affected with black-end from spoiling by harvesting green bananas and letting them soak in boiling water and can save fruit with cigar-tip rot by spraying copper fungicides.

References

• Purdue University: Banana - Diseases
• Floridata: Musa x paradisiaca