2019 ASHS Annual Conference

For some apple cultivars, inadequate red fruit color development can reduce crop value. We evaluated the effects of reflective groundcovers on light interception and reflectance, yield, and fruit quality of ‘Fuji’ apple in 2018. An experiment was conducted in a mature ‘Fugachee Fuji’/‘G.11’ planted at 2.1 x 4.3 m spacing at a commercial orchard in Edneyville, NC. Multiple reflective groundcovers were evaluated and installed five weeks before anticipated harvest. Woven reflective groundcovers (Beltech PD-2911 and Extenday™; 3.5 m width) were placed adjacent to 7-tree plots (15.2 m long section) on each side of the row. Mylar reflective groundcover (1.0 m width) was placed adjacent to 7-tree plots on each side of the row and positioned proximal to the drip line. The experiment consisted of four treatments with six replications arranged in a randomized complete block design. Tukey’s honest significance test was used to test mean separation among treatments at P = 0.05. When compared to the control, woven groundcovers (Beltech PD-2911 and Extenday™) significantly increased PAR reflected from the groundcover on the north and south side of the trees. UV radiation reflected from Extenday™ was 20.7 times greater than the control on the north side of the tree and 18.9 times greater on the south side. Mylar did not affect UV radiation reflection on the north side of the tree, but increased UV reflected radiation on the south side of the tree when compared to the control. UV radiation levels of Beltech PD-2911 did not differ from the control in any canopy position. Extenday™ was effective in increasing light reflectance of PAR and UV light in the orchard canopy resulted in a significant increase in the proportion of fruit with greater than 50% red fruit color. Beltech PD-2911 increased PAR reflectance into the canopy, but UV light reflectance (250 to 400 nm) and the proportion of fruit with greater than 50% red fruit color did not differ from the untreated control. Reflective groundcovers did not influence fruit maturity indices or sunburn incidence.