The first study, investigated the efficacy of a commercial biofilm designed to prevent rain-cracking in sweet cherries. Despite the product's intended use to supplement the fruit's natural cuticle, researchers found that repeated applications of Parka® did not increase the mass of the fruit's cuticle, nor did it alter its mechanical properties, such as strain relaxation. Most notably, the treatment failed to reduce water uptake or the incidence of fruit cracking compared to untreated controls.
In a parallel investigation involving apples, researchers explored whether feeding a cutin precursor could naturally stimulate cuticle growth. The study, tested the hypothesis that providing oleic acid-a primary building block of cutin-directly to developing fruit would enhance the protective barrier. The results showed that while the fruit absorbed the precursor, it did not lead to a measurable increase in cuticle thickness or mass. This suggests that cuticle deposition is strictly regulated by the plant's internal developmental programs rather than the availability of raw materials.
Together, these findings indicate that the fruit cuticle is a highly stable structure that is resistant to external manipulation during the growing season. For growers and researchers, this highlights the ongoing challenge of managing fruit integrity and suggests that future efforts may need to focus more on genetic selection or alternative environmental management rather than topical or metabolic supplements.
Professor Dr. Knoche is a professor of Horticulture at the Leibniz University of Hannover, Germany where he teaches and conducts research in fruit science. His research focuses on fruit surface disorders in a wide range of fruit crops including sweet cherry, apple, strawberry, grape, banana and mango.
The articles can be found on the ASHS HortScience electronic Journal website at:
https://doi.org/10.21273/HORTSCI18791-25 and https://doi.org/10.21273/HORTSCI18917-25
Established in 1903, the American Society for Horticultural Science is recognized around the world as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting and encouraging national and international interest in scientific research and education in all branches of horticulture.
Comprised of thousands of members worldwide, ASHS represents a broad cross-section of the horticultural community - scientists, educators, students, landscape and turf managers, government, extension agents and industry professionals. ASHS members focus on practices and problems in horticulture: breeding, propagation, production and management, harvesting, handling and storage, processing, marketing and use of horticultural plants and products. To learn more, visit ashs.org.
