Mandevilla vine

Question

My plant is dying the leaves are going brown up the middle along the spine and are dropping off I have used insecticidal soap as well as fungicidal spray nothing is working…help

• 

Answer 1

This sounds like a Fusarium Rot disease.
This article has more information.

https://www.gardeningknowhow.com/ornamental/vines/mandevilla/mandevilla-disease-problems.htm