EFFECT OF TRACE ELEMENT SPRAYS AND FRITTED TRACE ELEMENTS ON THE GROWTH AND MANGANESE, ZINC, COPPER, AND BORON CONTENTS OF YOUNG BRAESTAR/M793 APPLE TREES IN SAND CULTURE

Abstract

In a 21-month pot trial, year-old Braestar/M793 apple trees were subjected to a combination of foliar sprays containing manganese sulfate, zinc oxide, Solubor, copper oxichloride, and urea at rates, respectively, of 1.0, 0.5, 1.0, 0.25, and 2.5 g L⁻¹ water, and soil-applied fritted trace elements (FTE). The carrier (FTE-504Fe®) contained 7.5% manganese (Mn), 7.0% zinc (Zn), 7.0% copper (Cu), and 3.8% boron (B), and was mixed into the washed sand growing medium, before planting, at rates of 0, 100, and 200 g FTE m⁻³. Where FTE was applied at 100 g m⁻³ and foliar sprays were also applied, total tree dry mass (DM) and rootstock DM were significantly (p ≤ 10.05) greater, by 16% and 29%, respectively, than in the control which received no FTE and no sprays. Sprays without FTE had no effect on DM. Where FTE was applied at 200 g m⁻³, with sprays, stem diameters were 17% smaller than at the 100 g FTE m⁻³ application rate, implying oversupply. Oversupply of FTE at 200 g m⁻³ was marked in the unsprayed treatments where stem diameter and scion, rootstock, and total tree DM were smaller than in the control by, respectively, 16%, 31%, 20%, and 27%.

Acknowledgments