Season and cultivar influence the fruit quality response of apple cultivars to particle film treatments

Experiments were performed over 3 years to examine the effect that particle film (PF) treatment had on fruit quality of several apple (Malus x domestica) cultivars in Washington and West Virginia. In the first study, a highly reflective, white, hydrophilic particle-based kaolin mineral (Surround WP) was applied to 'Empire' apple in May and June, on a season-long basis, or not at all. Red fruit color was increased by both the PF treatments compared with no treatment in all years. In a second study, the PF material was applied, starting at petal fall, every week for 6 weeks and then every 2 weeks until harvest to 'Empire', 'Gala', and 'Fuji' trees in West Virginia and to 'Cameo', 'Fuji', and 'Gala' trees in Washington. In the latter study, cultivar response to season-long applications varied by year and location. 'Empire' consistently had improved red color with season-long applications of PF materials. 'Gala' had greater fruit weight and red color with PF application in I of 2 years in West Virginia but not in Washington. 'Fuji' had greater fruit weight and soluble solids content and 'Cameo' had greater soluble solids, higher starch indices, and greater red color in Washington with the PF application. In these studies, application of a PF never reduced the surface red color in apples. A taste panel did not identify quality differences in 'Empire' apples treated with PF vs. the control. Cultivar responses to PF applications were variable due to location and yearly environmental characteristics. While particle film technology has value for insect control and reducing sunburn, it has limited value to enhance fruit color due to the inconsistent response.