Cherry orchard management practices to limit fruit cracking and doubling
Cherries are particularly vulnerable to adverse weather. It can be challenging for growers to ensure quality fruit with the persistence of extreme weather events that cause fruit disorders such as rain-induced cherry cracking or heat events post-harvest that result in doubled fruits.
Cherry fruits are considered highly prone to cracking, which is one of the major limiting factors in production resulting in severe economic losses. Cherry cracking is characterized by the splitting of the fruit cuticle. When cherries near harvest, they accumulate more sugars in the fruit. If exposed to long periods of rain, dew or high humidity, the cuticle absorbs the water and when it can no longer contain the increasing sugar amounts it bursts.
There are several practices growers can implement to help prevent yield loss in their cherry crop.
Cherry cracking is closely associated to variety selection. Some varieties of cherries are more prone to resist cracking due to their genetic structure, which controls the form, composition and thickness of the cuticle. It’s recommended to choose cherry varieties that are resistant to rain-induced cracking. It is also important to know which varieties perform well in particular growing areas when selecting varieties for the orchard. Observing how a cherry variety responds to rainfall events can help with future management decisions.
Enhance cuticle protective properties
The sensitivity to cracking varies with cuticle properties. The fruit cuticle is a hydrophobic and semi-permeable membrane consisting of two layers: the cutin and cuticular waxes. The cuticular waxes play an important role in the water permeability of cherries. Cherries with a higher wax content are more resistant to the incidence of cherry cracking. By incorporating a cuticle supplement into your crop protection program, you can help protect fruit from cuticular cracking. Cuticle supplements prevent the uptake of water through the cuticle by coating fruit with a hydrophobic lipid bilayer. This added layer not only provides hydrophobicity that repels water from the fruit surface, it also seals cuticular microfractures that can lead to fruit cracking.
Cuticle supplements can also be used post-harvest to reduce doubling for the following growing season. Doubling is a deformation of the fruit that results in two equally sized cherries that are insufficiently separated or one underdeveloped fruit protruding from a normally sized one. Either way, they are usually culled, resulting in lost profit. Doubling is most likely to occur when trees are subject to heat stress four to six weeks after harvest.
Applications one to two weeks post-harvest help to supplement and strengthen the leaf cuticle of the cherry plant. This allows the plant to focus on increased chlorophyll production, resulting in better overall tree performance which helps to reduce the impact of heat stress on the tree when temperatures begin to rise, ultimately decreasing the number of doubled fruits the following season.
Irrigation management to minimize stress
High temperatures can increase the incidence of fruit cracking due to the increased rate of water uptake and fruit transpiration. Dry conditions caused by high temperatures can make the fruit cuticle more vulnerable to cracking due to the inelasticity of the cuticle. Minimizing stress by implementing a proper irrigation management plan to avoid water stress at late stages of fruit growth can improve resistance to cracking.
Crop load management can be successful in mitigating cracking without compromising fruit size. Manipulating the number of fruits on the tree by pruning has been used to encourage larger and sweeter fruit. However, yield loss due to cracking can be significant in those trees. Trees with low crop loads that have larger cherry fruits are more prompt to crack than those from trees with medium to high crop loads. Maintaining a medium or high crop load can help to reduce the incidence of cracking.
While it can be difficult for cherry growers to anticipate how vulnerable the fruit will be each growing season with variable weather, proactive orchard management and a focus on cuticle care can help growers achieve better fruit quality, resulting in increased marketable yield at harvest time. Talk to your Cultiva representative to learn how you can maximize production and quality of cherries this growing season.