Kaolin-based particle film sprays reduce the incidence of pests, diseases and storage disorders and improve postharvest quality of 'Delicious' apples

Several pests and diseases infest apple during production, potentially causing heavy losses. Numerous pesticides are used to control pests and diseases, sprays of which contaminate the environment and result in pesticide residues. Among Good Agricultural Practices (GAPs), particle film technology (PFT) is promising for organic fruit production. Now some kaolin-based PFs such as Surround WP (R), Eclipse(T), Anti-stress-500 (R), Parasol (R) have been developed which are available worldwide for commercial use. In India, preliminary research work was conducted for observing the effect of one kaolin-based PF (Surround WP (R)) on 'Delicious' apple. Five sprays of Surround WP (R) (3%) were applied to 20-randomly selected 'Delicious' apple trees each year during 2015-16 and 2016-17. The sprays were applied, starting on June 15 every year at fortnightly intervals and 20 unsprayed trees served as controls. Surround WP (R) reduced the incidence of San Jose scale (by similar to 64%), apple scab (by similar to 87%) and powdery mildew (by similar to 78%) significantly but increased the incidence of woolly apple aphid (by similar to 23%) compared to the control. Surround WP (R)- treated apples developed a better red color (Hunter 'a' value = 53.42 +/- 0.42), increased anthocyanin content and improved appearance score. Surround WP (R) - treated apples were 35.4% firmer and contained a 49.9% higher Ca content compared to untreated fruit. Surround WP (R) treatment also showed significant improvement in soluble solids (increased by 10.5%) and ascorbic acid content (increased by 10.8%) with significant reduction in storage disorders such as bitter pit (reduced by 90.8%), brown core (reduced by 73.3%) and water core (reduced by 88.4%). Based on this study, Surround WP (R) can be recommended for organic production of 'Delicious' apples in Himachal Pradesh, India.