Ailanthus, commonly known as tree-of-heaven but more appropriately called “stink tree” due to the pungent order of its crushed foliage, is an introduced invasive common in eastern mixed oak forests. Since it is a rapidly growing and prolific tree, it often displaces native plants and disrupts forested ecosystems. It is very challenging to control chemically because it is a prolific sprouter; however, there may be an alternative biocontrol in the near future. A native soil-borne fungus, Verticillium nonalfalfae, which was discovered in Pennsylvania by Penn State researchers, is very specific and deadly to ailanthus but not to more than 75 other woody species. In a trial on the Wayne National Forest in Ohio, three Ohio state forests and a private, non-profit wildlife conservation center, researchers are testing the effectiveness of the fungus in killing ailanthus as well as monitoring subsequent regeneration. To date, control has been effective with no off-target effects being observed. Forest Service scientists are continuing to formally study nontarget effects before large-scale releases into forest environments begin. Scientists are also investigating ways to streamline the production of inoculum by developing improved and expedient culturing methods of fungal spores; existing production methods take three to four weeks to complete and are labor intensive.