What is this disease in Tree Drumstick

[ganesh1960]

Good evening to all.
I have 2 year old drumstick trees in Vellore district near Kalavai.This variety was bought from Mr.Alagarsamy of Pallappatti. Most of the trees are having a whitish ash colour rough uneven formation on the stems

as shown in the attached photos.Could any one help me rectify this disease.