267 Improving Red Color on Apples with a Reflective Groundcover

Abstract

In many years, apples grown in the mid-Atlantic region fail to exhibit a high percentage of the dark red color that buyers and consumers desire. In 1996, we initiated studies to examine the use of a metalized silver low-density polyethylene reflective groundcover (RGC) to improve red color on several apple cultivars under several training systems. A RGC placed in the orchard drive middle of 8-year-old `Delicious' apple trees trained to a “Y” trellis increased the percent surface red color and resulted in darker, more red-colored apples at harvest. A RGC increased surface red color on `Empire' apples on a “Y” trellis, but on central leader-trained semi-dwarf and standard size `Empire' showed no effects on color. Central leader-trained `Fuji'/EMLA.7 apples with a RGC had more red color than untreated fruit at harvest. In 1997, RGC placed under the canopy of 3-year-old `Fuji' trees trained to a “Y” trellis increased the full sunlight on the underside of the canopy by 28%. Ambient air temperatures within the RGC illuminated canopy averaged 2.1 °C higher than the non-RGC canopy. The level of percent full sunlight was increased within the canopy of well-pruned 32-year-old `Miller Spur Delicious' apple trees 4- to 8-fold with RGC placed in the row middle or under the canopy in a commercial orchard in 1998. Position of the RGC to the canopy affected fruit red color response differently between the lower and upper part of the canopy. Bins of fruit graded with a commercial color sorter showed no difference in fruit color; however, there was a strong trend toward increased red color where the RGC material was applied.