Home Industry News Economics Split and Cracked Berries Observed in Missouri Vineyards

Split and Cracked Berries Observed in Missouri Vineyards

Some growers are reporting split or cracked berries after rainfall events and or hail (Figure 1). Berry splitting or cracking can occur from weather related conditions and from physiological disorders. When trying to determine what caused the damage take the following into consideration.

If split or cracked berries are only found on the front side of a cluster and only on one side of trellised grapevines, then damage can be attributed to a hail event. Also look at the leaves, hail damaged leaves typical have holes and appear tattered.

If split or cracked berries are found distributed throughout the cluster on both sides of a trellised grapevine, then damage could be attributed to a number of physiological or weather related events. For example, high temperature weather results in berries having thin skins. Grapes under drought conditions followed by high rainfall results in the grapevine taking up more water resulting in cracked berries.

In short, some of these damaged berries will dry-up and fall to the ground. Some berries will scar and heal-over. However, keep an eye on split or cracked berries for disease development.

Berry Cracking

In most all cases of early season berry cracking the cracking of berries is the result of environmental factors interacting with the berries.

There are three main environmental factors that have a role in berry cracking. High berry temperatures result in reducing the strength of the berry skin, the berry expands, and the berry skin surface area shrinks. This results in berry cracking. Berry clusters that are shaded by the canopy often do not experience berry cracking as the canopy reduces berry temperature.

High relative humidity especially at night can result in berry cracking. During the nighttime plant transpiration from the grapevine leaves is reduced compared to the daytime. At night time the grape berries continue to transpire and this increases turgor pressure on the berry skins and results in berry cracking. During the day the leaves are transpiring high amounts of water and this lessons the turgor pressure on the grape berry skins.

Rain or heavy dew can induce berry cracking. Water can enter the berry by root uptake via transpiration. In vineyards that have experienced a drought period followed by a heavy rainfall event, this can result in increased turgor pressure on the berry skin resulting in cracking. Water can also enter a berry by two other mechanisms. Water can enter a berry by moving across the berry skin or water can enter from the berry stem receptacle with the water moving in due to transpiration of the berry. At present time the mechanism causing the water to move into the berry from receptacle has not been elucidated.

Other factors have been identified that cause fruit cracking besides environmental conditions. Powdery mildew infections on the berry skins cause microfractures in the cuticle making the berries prone to cracking. Calcium deficiency has also been implicated in berry cracking. Calcium is important in maintaining the integrity of cell membranes. In addition, calcium plays a role in the membranes structure and regulates water permeability of the membrane. When calcium is deficient cell membranes deteriorate.

Good viticulture practices that begin with site selection will often alleviate berry cracking. Vineyard sites that shed water quickly and have well drained soils will lesson the impact of large rainfall events. Limiting canopy management, especially the removal of leaves that exposes fruit berries to intense sunlight and high temperatures can reduce berry cracking. Monitoring grapevine calcium levels at bloom can determine if a calcium deficiency exists. Calcium deficiencies can be corrected with foliar applications of calcium. Berry cracking can also be inherit to a cultivar such as Vignoles which the berries often crack near harvest as a result of a rainfall event.

Bottom line: Management of split or cracked berries

  1. Important to watch for potential disease-rot development. I surmise that early season split or cracked berries will likely drop from the cluster or scar-over and heal.
  2. If rot develops, consider applying a strobilurin fungicide if needed such as Pristine. Reminder strobilurins should only be applied no more than two times during the growing season and never consecutively. — By Dean Volenberg, University of Missouri Grape & Wine Institute

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