Abstract

Biostimulants are intended to reduce stress associated with non-dormant (summer-dug) harvest of field-grown nursery stock; however, the effectiveness of biostimulant treatment is uncertain. We tested the effects of three application methods of Bioplex™ (a biostimulant) on transpiration rates, transplant survival, and recovery of field-grown goldenraintree (Koelrueteria paniculata Laxm.), which is considered difficult to transplant and is rarely summer dug. Bioplex™ was applied as a foliar spray, soil drench, or a combination of foliar spray and soil drench. Bioplex™ reduced transpiration rates of trees by 12% compared to untreated control trees. Root loss associated with digging reduced transpiration rates and had a greater effect on transpiration than any Bioplex™ treatment. Survival 12 months after transplanting was 100%. Bioplex™ treatments applied before digging had no effect on growth after transplanting. Transplanted trees had reduced caliper growth and shoot extension the season after transplant compared to non-dug controls. Although Bioplex™ reduced transpiration rates for three to five days after application in non-dug trees, there were no long-term benefits to survival or re-growth to summer transplanted trees.