L. I., Brooklyn, N. Y. The Verbena rust is not a new trouble, though some years it is much more prevalent than others. This year and last it has almost disappeared. It is not an insect as you suppose which causes the rust, but a small fungoid parasite, Erysiphe verbenas. It was first discerned and its true character made known, with the name as above by Schweinitz an eminent botanist of the early part of the present century. Curious mites have been found in connection with the rust, and some have supposed them to be the cause of the trouble.