Sweet cherry cracking caused by rainfall remains a major production challenge in many growing regions worldwide. Fruit nearing harvest is particularly susceptible, as rapid expansion during the final stages of development places significant strain on the fruit surface. For growers, this narrow window between final fruit maturation and harvest represents the most vulnerable stage of the production cycle, when a single rain event can cause severe cracking and substantial losses in marketable yields.

While rainfall often triggers cracking at this point in the season, the underlying causes result from complex interactions between fruit physiology, environmental conditions and the structural properties of the fruit cuticle. Understanding the relationship between these three factors is key to developing an effective strategy to minimize the risk of cracking.

Microcracking: A Hidden Driver of Cracking

Cherry cracking is influenced by multiple interacting factors, including rainfall intensity, humidity, temperature, sun exposure, fruit maturity, cultivar susceptibility, irrigation practices and overall orchard management. Two primary types of cracking are recognized: cuticular and vascular, with cuticular cracking being the most common.

Cuticular cracking begins with microscopic fractures in the fruit cuticle, commonly known as microcracks. These small defects often form during the early fruit development stage and, although invisible to the naked eye, create weak points in the fruit surface. During rainfall, water can enter through these weak points, increasing internal pressure within the fruit. This can cause the fruit skin to expand beyond its capacity, leading to visible cracks that make the fruit unmarketable.

Cracking most often occurs during the final stages of cherry development, as fruit approaches full maturity. During this final phase of fruit development, commonly referred to as Stage III, cherries undergo rapid expansion as cells enlarge. At the same time, the outer surface of the fruit must maintain structural stability, despite increasing internal pressure.

Because the cuticle serves as the primary barrier regulating water movement and protecting the fruit surface, its condition plays a critical role in determining the fruit’s susceptibility to cracking.

The Importance of the Fruit Cuticle

The cuticle provides a protective outer layer that shields fruit from environmental stress, while regulating water movement, gaseous exchange and nutrient transport. Composed primarily of waxes and lipid-based compounds, the cuticle is formed during early growth stages and stretches as the fruit expands.

Maintaining cuticle integrity is a key factor in reducing susceptibility to rain-induced cracking. As cherries expand, the cuticle experiences increased mechanical strain. Environmental factors such as fluctuating humidity, temperature shifts and rainfall can place additional strain on cuticle stability. Compromised areas may develop microfractures that serve as entry points for water during rainfall events, boosting the risk of cracking.

Thankfully, solutions and strategies are available to maintain or reinforce the cuticle, helping reduce susceptibility and protect fruit quality.

Supporting the Cuticle with Parka^®

One approach to supporting cuticle resilience is Parka. Parka is a phospholipid and polysaccharide-based plant health solution that enhances the fruit and leaf cuticle. It is designed to supplement the naturally occurring cutin and waxy layers of the plant’s cuticle.

Applied as a foliar spray, Parka forms a clear, elastic supplemental lipid bilayer on the fruit’s surface. This supplemental barrier expands as the fruit develops, helping maintain flexibility and structural stability during critical growth stages. By reinforcing this natural barrier, Parka helps reduce the formation of microcracks that often lead to cuticular cracking.

Parka also influences water interactions at the fruit surface. Its hydrophobic properties encourage water to shed from the fruit, reducing prolonged surface wetness that can contribute to cracking during rainfall events.

Parka has been rigorously tested and evaluated by university researchers and in commercial cherry orchards across multiple growing regions, including North America, South America and Europe. These diverse environments expose fruit to a wide range of climatic conditions, providing valuable data and insights into its performance.

Under natural rainfall conditions, cherry cracking was reduced by 48% on average across 15 trials conducted over 10 years, covering eight varieties globally (Bing, Skeena, Sweetheart, Lapin, Coral, Brooks, Ziraat, Early Burlat).

Because the physiological drivers of fruit cracking are consistent across species, these results extend beyond cherries. In blueberries, Parka delivered a 54% average reduction in cracking across eight trials over eight years, spanning six global varieties.

Proper application timing is critical to maximizing the performance of Parka, since protective cuticular layers are formed during early stages of fruit development when the fruit is most vulnerable. Best results are achieved by supplementing the cuticle early with Parka to help repair and prevent the development of microcracking, which causes fruit cracking.

Integrating Parka into Orchard Management Programs

Successful cracking management rarely relies on a single solution. Instead, adopting integrated orchard management programs that address multiple factors, including plant health and environmental exposure, help optimize cracking mitigation.

Practices such as balanced irrigation management, canopy structure optimization and proper nutrient management all contribute to overall fruit resilience. Parka complements these practices by providing an additional layer of protection during the fruit’s most vulnerable period.

While no single tool can eliminate the risk of rain-induced cracking under all conditions, strengthening the fruit’s natural barrier plays an important role in reducing susceptibility. By supporting cuticle integrity during periods of environmental stress, Parka provides growers with an additional measure of protection against rain-induced cracking. Ultimately, when used as part of a proactive program, Parka can help maintain fruit quality and protect marketable cherry yields.

At Cultiva, we recognize the need to better understand fruit-cracking physiology, especially for cherries. We continue to work with researchers and growers around the world to develop and test tools that help protect fruit quality across numerous challenging growing environments.