Calcium Spray Materials and Fruit Calcium Concentrations Influence Apple Quality

Abstract

Bearing ‘Delicious’ and ‘Golden Delicious’ apple trees in three northcentral Washington orchards were treated with up to 12 calcium (Ca) spray materials over five years to determine their effect on fruit quality. In most cases, Ca spray materials, with the notable exception of CaSO ₄, increased Ca concentrations in the fruit cortex and peel, and reduced the incidence of bitter pit and scald. Fruit firmness and to a lesser extent titratable acids were frequently enhanced with Ca spray materials, especially CaCl ₂, but soluble solid concentrations were seldom affected. In ‘Delicious’ apples, fruit appearance and to a lesser degree total red skin area and internal browning control were improved with sprays of CaCl ₂or Stopit. None of the Ca spray materials caused unacceptable russet markings on the fruit, but some Ca spray injury occurred on leaves, especially ‘Golden Delicious’ with the exception of CaSO ₄sprays. There was also no apparent affect of Ca sprays on fruit size. Therefore, certain Ca sprays, especially CaCl ₂-based materials are advantageous for improving fruit quality of ‘Delicious’ and ‘Golden Delicious’ apples.