LEAF AND FRUIT DEVELOPMENT OF `EMPIRE' APPLE TREES AS INFLUENCED BY SHADING AND FOLIAR MICRONUTRIENTS.

Lower scaffold branches of `Empire'/M.7 apple trees which were planted in 1975 and trained as Central Leaders were shaded or left exposed from 1986-1988. Foliar micronutrient sprays of N, Zn and B were applied 3 times in the early season of each year to both shaded and exposed scaffold branches in an attempt to improve spur vigor. In 1988 spur and bourse shoot leaf area development and fruit growth were monitored. Shading resulted in greater initial spur leaf area at 3 weeks after bloom but shorter leaf duration. Spurs on shaded branches had lost 2/3 of their leaf area by 11 weeks after full bloom while exposed branches had lost only 25%. Bourse shoot leaf area was greater on exposed branches throughout the season. Foliar sprays of micronutrients did not increase leaf area or leaf duration of either spur leaves or bourse shoot leaves. Fruit growth rate was reduced by shading most in the early season. Final fruit size, color, soluble solids and dry matter were reduced by shading. Foliar micronutrient sprays did not affect fruit growth rate any time during the season or final fruit size, color, soluble solids and dry matter. There was also no interaction of shading and foliar nutrition on fruit size or quality. It appears that the negative effects of shading on spur vigor and fruit quality cannot be reversed by foliar micronutrient sprays.