My old lilac tree has some suckers shooting straight up and they have some nice looking buds on them. I know I'm suppose to cut these off. Can someone please tell me when I should remove them? and where I should make my cut? but most importantly WHY do we remove suckers? What exactly are they and their purpose? Are they detrimental to the tree? I sure hope this isn't a dumb question... I thought maybe they might make my tree bushier? Please educate me on this. Thank you everyone.