Peel splitting is often caused by extreme fluctuations in soil moisture as well as temperature and humidity.
During a hot, 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. Fruit splitting also occurs when long, wet periods are followed by dry spells. Minimizing stress by correct irrigation and reducing crop load can reduce physiological stress and splitting in susceptible cultivars.
Trees that are deficient or low in potassium and calcium can result in fruit skins that are either too thin or which are structurally weak and more prone to these stresses. Therefore, improved potassium and calcium supply can minimize splitting.
Crop Nutrition and Citrus Peel Splitting
Better calcium supply, through soil and foliar applications during summer, also minimizes risks. In the trials shown, sprays a month before and then when splitting is seen, helped reduce the number of split fruit.
Calcium nitrate sprays applied to the fruit must cover the whole fruit surface to be effective.