Charlie does this and he is the sweetest dog. He does not like skateboards, big wheels, scooters, motorcycles or big garbage trucks. He doesn't growl, but he barks and lunges. Niner doesn't really care. I've worked long and hard on this and since he is so treat motivated I can usually distract his attention from the enemy (LOL) with a treat. Sometimes I give him a firm "NO" as the situation comes near he will be good, but sometimes he doesn't listen and will bark and lunge. I do think it is a fear factor - not aggression. Try using some really good treats to distract Daisy. Now that you know those things bother her you can work on distracting her.
Nancy