There are few/no diseases that prove fatal to Fringetree on their own, but in combination, they can significantly reduce vigor and health. Occasionally scale and borer have been reported, as well as leaf spots, powdery mildew, and canker. In southeastern states, it’s a larval host for the Rustic Sphinx (Manduca rustica), Waved Sphinx (Ceratomia undulosa), and Laurel Sphinx (Sphinx kalmiae) but these moths are only native to the White Fringetree’s native range; you won’t find one up here in Wisconsin.
The White Fringetree is in the family Oleaceae, the same family as the ash species, and was reported as the secondary host of the Emerald Ash Borer (EAB). However, researchers at Wright State University have found that White Fringetrees in low-density ornamental landscapes were not a significant reservoir for EAB. To further support this observation, a study conducted from 2015-2018 published in Environmental Entomology found that White Fringetrees are likely to withstand attacks by emerald ash borer. The majority of the White Fringetrees analyzed did not become infested. For the ones that did, the majority survived. Scale can be controlled with horticultural oil sprays. As mentioned in Maintenance and Care, planting in dry conditions can lead to Botryosphaeria dieback.