Supplemental Nickel Corrects Mouse Ear Disorder of Bitternut Hickory

While sought after for use in managed landscapes, bitternut hickory [Carya cordiformis (Wang.) K. Koch] remains underutilized in horticulture due its reputation for difficulty with production and transplanting. After learning of issues experienced by growers and observing deformed leaf development of container-grown stock, we examined effects of supplemental nickel applications on seedlings of bitternut hickory. We hypothesized that, like the closely related species pecan [Carya illinoinensis (Wang.) K. Koch], bitternut hickory would be similarly limited in production by a susceptibility to mouse ear disorder as a function of nickel deficiency. Seedlings cultivated with a soilless substrate in 3.8L (#1) nursery pots were treated with either a substrate drench or foliar spray of Nickel Plus® two weeks after budbreak. After 30 days, plants treated with a drench or foliar spray exhibited increased leaf area and decreased number of leaves per unit shoot extension and leaf greenness compared to nontreated controls. Foliar treatments resulted in an 83.5% increase in shoot extension over nontreated controls. Whereas seedlings provided supplemental nickel displayed healthy foliage after treatment, nontreated seedlings exhibited traditional symptoms of mouse ear disorder. These data indicate bitternut hickory is susceptible to mouse ear disorder, an issue remedied by supplementing nickel. Index words: foliar spray, substrate drench, soilless substrate, nursery production, ornamental plants. Chemicals used in this study: nickel lignosulfonate (Nickel Plus®). Species used in this study: bitternut hickory, Carya cordiformis (Wang.) K. Koch