Q.how to propagate dusty miller
I have dusty miller growing wild. Can I root it in water to make more plants from the cuttings, as I should trim the growth and it pains me to discard the trimmings.

You can use cuttings from dusty miller to propagate the plant, but you don't root it in water. You root it in a soilless media (perlite, verimulite, sand, peat moss, etc.)
This article will tell you how to prepare the dusty miller cutting and root the cutting:
http://homeguides.sfgate.com/propagate-dusty-miller-20455.html
Additional information on rooting plant cuttings can be found here:
https://www.gardeningknowhow.com/garden-how-to/projects/rooting-plant-cuttings.htm
For more information about the dusty miller plant, please visit the following link:
https://www.gardeningknowhow.com/ornamental/foliage/dusty-miller/growing-dusty-miller.htm