Strengthening the Cuticle Reduces Cracking and Doubling
Cherry cracking reduces yield and fruit quality causing significant economic loss for growers. Along with cultural practices such as row covers, soil covers, and irrigation management, cuticle supplements can play a large role in reducing cracking. Parka supplements the cuticle of the cherry, coating it with a clear, hydrophobic, and elastic lipid bi-layer that expands along with the developing fruit. This layer fills in microfractures as soon as they begin to develop. Parka also increases cracking resistance by enhancing cell membrane stability within the cuticle.
Doubling of fruit also results in significant culls, and as summer temperatures continue to trend upward, the need for prevention tactics is increasing. Heat stress is known to cause deformation of flower buds and subsequent fruit doubling the following year. When applied to cherry trees postharvest as flower buds begin to form, Parka increases the plant’s ability to combat stress and ultimately decrease the number of doubled fruits the following season.
Why use Parka on Cherries?
- Proven to reduce cracking damage by up to 50% over control.
- Reduces fruit doubling by up to 64% over control.
- Increases fruit quality and storage ability.
- Easily tank mixed with foliar nutrients and pesticides
- Leaves no visible residue.
- Exempt from maximum residue levels.
- Zero preharvest interval, zero worker reentry interval.
How to Use Parka in a Program
For cracking prevention, Parka should be applied to cherries at fruit set and again at straw color. Early applications help prevent the development of microfractures responsible for fruit cracking. A third spray is recommended if a rain event is expected more than 10 days after the second application.
For doubling reduction, apply Parka 10 days postharvest and again 20 to 25 days later.
What Causes Cracking?
There are two types of cherry cracking: cuticular and vascular. Cuticular cracking occurs when the cherry fruit absorbs surface by osmosis which is facilitated by cuticular microfractures. As sugar concentration increases during ripening, so does the osmotic potential (absorption potential) and the longer water remains on the surface, the more the fruit can absorb. Often, this type of cracking appears on the shoulders of the fruit when water pools in the stem bowl or at the blossom end where water droplets can form. This is the most common type of cherry cracking and it can occur with as low as 0.10 inches of rainfall in one event.
Vascular cracking is caused by water that is taken up by the roots and translocated through the vascular system. If more water is absorbed than the fruit can hold, the turgor pressure in the cells builds to the point where the fruit cracks from within. This type of cracking usually occurs after high-volume rain events followed by warm temperatures.
How Does Parka Prevent Cracking in Cherries?
Parka coats the fruit with an elastic, hydrophobic lipid bilayer, which seals the microfractures as soon as they appear, and if applied at fruit set, prevents their formation. Because Parka is hydrophobic, it also repels water from the fruit surface. Parka also increases the concentration of anthocyanins within the cuticle. These are antioxidants that reduce oxidative molecules that degrade membranes within the cells. By supplementing the cuticle and adding elasticity to it, as well as repelling moisture from the fruit surface and increasing cell membrane stability, Parka contributes to better cracking resistance.
What Causes Doubling?
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 occurs when the trees are subject to heat stress four to six weeks after harvest. This is a critical period when the pistil differentiation occurs within the flower buds that are forming for the next year’s crop. The minimum threshold temperature is around 94° F for doubling to occur.
At these temperatures, without cooling measures or other stress-reducing practices, the pistil of the flower will double and produce two incomplete cherries the following season.
How Does Parka Prevent Doubling?
Parka, because it supplements and strengthens the leaf cuticle, and increases chlorophyll production, significantly reduces the impact of heat stress on the tree. Under extreme heat stress, plants slow down or nearly stop all their developmental processes in order to conserve resources. When this happens during flower bud formation, the pistil does not fully divide. By strengthening the leaf cuticle, increasing the amount of chlorophyll, and reducing transpiration from the leaf, Parka applications allow the tree to continue photosynthesizing and support flower development.
What Do Growers Like About Parka?
Primarily, growers like Parka because it is effective. Reducing cracking by up to 50% and doubling by as much as 64% over control helps protect profits. In addition, Parka is easily tank mixed with many other inputs, including fertilizers and pesticides, which saves fuel and labor costs. Parka has an excellent worker safety profile with a zero preharvest or postharvest interval, and no maximum residue level. Parka is transparent and does not leave a white residue on the fruit, which workers and packers appreciate.