During a dry period the peel will turn fairly inelastic. When this is followed by irrigation or rain, a large amount of water is taken up into the fruit, forcing the rind to burst at its weakest point.
Minimising stresses by correct irrigation and reducing crop load (pruning) can reduce physiological stress and splitting in susceptible cultivars. Choice of cultivar can also have an effect particularly where late season rainfall exacerbates the problem. Crop nutrition also plays a major role in reducing fruit splitting or cracking.
Fruit with high levels of calcium and boron in the skin have a greater firmness, stronger cell walls and are much less susceptible to cracking/splitting. Nutrient sprays used pre-harvest will also improve the osmotic gradient across the fruit skin, minimising the flow of water into the fruit.
Calcium sprays targeted to the fruits increased the calcium content and helped to reduce cracking in sweet cherries and plums.
Copper also has a major effect on thickening the cell wall and improving skin strength, maintaining the integrity of the fruit. It does so through improving the lignin, pectin, cellulose and insoluble alcohol content of the cell wall. Appropriate high rates of copper applied as a series of sprays at 3 and 6 weeks after bloom, gave the best responses. The end result, as seen in trials in cherries, is reduced cracking.
Too much nitrogen, however, can reduce skin thickness. Excess nitrogen use will increase split pit in peaches. Thus, over-use of nitrogen increases the risk of damage during picking, storage and transportation, reducing fruit marketability and shelf life.
See our fertiliser programmes for different orchard crops, both top fruit and stone fruit, begin by choosing your crop.
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