White Substance on Branches of Lilac Bush

Question

What is the white substance (looks like a white power) on the bottom going toward the to of the branch.  Will it kill the lilac? What, if anything, can be done? Thanks for any help.
Olga West

Answer 1

It has powdery mildew. These articles will help:
https://www.gardeningknowhow.com/problems/get-the-cure-for-powdery-mildew.htm
https://www.gardeningknowhow.com/plant-problems/disease/powdery-mildew-homemade-and-organic-remedies.htm