Parka is specifically developed as a phospholipid based, hydrophobic, permeable, and elastic coating that mimics and supplements the plants natural cuticle.
Parka supplements a plant's cuticle
Considering the cuticle of the whole plant, not just the fruit, Parka increases the entire plant's tolerance to environmental stress.
Originally developed by researchers at Oregon State University, Parka is now used commercially on multiple crops to suppress rain cracking, improve fruit quality and finish, and increase marketable yields.
Parka for pome fruit
Parka has demonstrated improvements in colouring, finish and quality.
During cell elongation the apple is expanding rapidly causing the cuticle to be continually fractured. Applications of Parka can fill in fractures and enable the cuticle to better expand with fruit growth.
With Parka having effect on the whole plant via the cuticle on foliage and fruit, this reduces the impact of heat stress and improves colour development by elevating anthocyanin levels in apples.
Parka treated fruit have less lenticel marking and calyx end cracking.
Parka is an alternative to the organosilicon used with Retain. Retain performance is unaffected, but there is no lenticel marking that is seen with the organosilicons, especially on apples that have sensitive skin.
See this article and contacts in Tree Fruit May 2019