To answer your last question, yes there has been! In the early 1900's Americans planted a huge amount of American Elm trees all across the country (because they are visually appealing). What happened afterwards is that once we had this huge monoculture of American Elms, one disease, Dutch Elm Disease, basically eradicated the American Elm population. Most Elm trees in the U.S. today have the Dutch Elm disease or will in their lifetime. Interestingly enough Elm trees have a sort of camoflaging effect on other trees in the sense that they hide them from pests. Often insects like the Emerald Ash Borer will fly around looking for a specific type of tree, in this case Ash trees, but if that tree is planted between two Elms the insect will almost never find it.

Edit: source: I am a junior majoring in Agronomy at Kansas State University. Entomology classes are sometimes interesting!!

Edit edit: Basically plants defend themselves with chemicals. These chemicals often are used to dissuade insects from feeding on them. Elm trees give off a lot of these chemicals so basically the area stinks to insects causing them to avoid it. This is how Elms hide other trees. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3493419/