Weeping willow has orange powder on leaves what is it how do i get rid of it?

the orange powder is only on the underside of the leaves please could some one help thanks .sandraWeeping willow has orange powder on leaves what is it how do i get rid of it?
It is a fungus called rust. It usually will not hurt the plant, unless it becomes very bad. then a fungicide application may be necessary. It is very common in lawns, and sometimes seen in trees. Most of the time it will simply go away with a change in weather conditions. If your tree starts dropping leaves I would contact a tree care company in your area for possible treatment.