American persimmon (Diospyros virginiana L.) is a multipurpose tree endemic to the eastern United States with potential for broader use in managed landscapes or for producing desirable fruits. Whereas most members of this genus originate from tropical and subtropical regions, the American persimmon could expand landscape diversity and fruit production applications in northern climates. Due to purported challenges with transplant success, American persimmon is likely best suited to cultivation in containers. Recent observations of container-nursery crop production indicates American persimmon is susceptible to mouse ear disorder (MED), a function of nickel deficiency. We hypothesized that American and Asian-origin persimmon species are susceptible to MED and that supplementing nickel with a foliar spray will ameliorate the disorder. Our objectives were to characterize symptoms of non-treated MED with American (D. virginiana), Japanese (D. kaki), and dateplum (D. lotus) persimmon as well as to determine if MED could be corrected by foliar application of nickel or other compounds presumed to interact with the urease metabolic pathway, such as urea. In a randomized greenhouse study, seedlings of American, Japanese, and dateplum persimmons were evaluated by comparing a non-treated control (H2O spray), to foliar spray treatments of NickelPlus® (169 ppm), NiCl2 (169 ppm), urea (0.325 g/L), and combined NiCl2 (169 ppm) and urea (0.325g/L). Following treatment, plants were evaluated using a MED severity rating scale, leaf characterization metrics (greenness, count, surface area, dry mass, and specific area), as well as metrics characterizing stem traits (elongation and dry mass). Compared to the non-treated control, leaf surface area increased by ~56%, ~61%, ~25%, and ~52% for the Nickel Plus®, NiCl2, Urea, and combined NiCl2 Urea treatments, respectively, when pooled across species and cultivar. These results suggest nickel supplements are effective at increasing important growth metrics like leaf surface area for Diospyros species displaying MED symptoms. This study offers valuable insights for improving the cultivation of persimmons in container nursery production settings, contributing to the development and advancement of American persimmon as an emerging specialty crop.
