How to Prevent Pomegranate Fruit Cracking? A Full Breakdown of Practical Methods
Fruit cracking is a prominent problem commonly found in pomegranate production. It can occur from the young fruit stage to the mature stage, and is most severe in the 10-15 days before harvest. In mild years, the fruit cracking rate is generally 3-9%, while in severe years it reaches as high as 30-75%; after the fruit cracks, it is prone to rotting and cannot be kept fresh for storage, so its commercial and edible value is reduced or lost, causing major economic losses. The preventive measures are:
1. Select cracking-resistant varieties. Pomegranate fruit cracking is related to varietal characteristics. Generally, varieties that mature early, have flat-round fruit shapes, and have thin, easily aging rinds are prone to cracking; varieties that mature late, have green or copper-colored rinds, and have thick, rough, rusty-colored rinds are less prone to cracking. Varieties promoted in production, such as Linxuan No. 8, Linxuan No. 14, Taishan Hong, Yu Pomegranate No. 1, Yu Pomegranate No. 2, and Yu Pomegranate No. 3, all belong to excellent varieties with relatively strong cracking resistance.
2. Choose the orchard site reasonably. Pomegranate fruit cracking is related to site conditions. Generally, in soils with a shallow plow layer and thin active soil layer, pomegranate trees grow poorly, yields are low, and fruit cracking is severe; in deep plow-layer soils, pomegranate trees grow well, yields are high, and fruit cracking is mild. Irrigated land has mild fruit cracking, while dry sloping land has severe fruit cracking. In addition, sticky, heavy-textured soil has poor aeration, and fruit cracking is also severe. Therefore, when planting pomegranate trees, it is advisable to choose plots with deep soil layers and irrigation conditions; if building an orchard on dry sloping land, soil improvement should be carried out, and soil and water conservation should be done well to prevent soil erosion.
3. Prune reasonably. The purpose is to improve ventilation and light penetration in the orchard through pruning, promote coloring, and prevent fruit cracking. During winter pruning, remove or cut back some larger crossing branches and overlapping branches, adjust the subordinate relationships among backbone branches at all levels, and thin out and cut back dense fruiting branches and weak, drooping branches on the periphery; summer pruning mainly consists of bud removal, pinching, and branch pruning. Remove useless and densely crowded buds and branches early, promptly thin out useless water sprouts, and branches with space can be transformed into fruiting branches through pinching and twisting.
4. Orchard mulching. In the early stage of fruit growth, covering the tree disk with plastic film or crop straw helps maintain soil moisture, prevent orchard soil compaction, and reduce pomegranate fruit cracking. In addition, interplanting green manure, beans, or other low-stalk economic crops in the pomegranate orchard has the same effect.
5. Reasonable fertilization. Pomegranate irrigation should follow the principles of small amounts, balance, multiple applications, and appropriate control. In production, generally during the stage of rapid young fruit growth or expansion, irrigate once every 10-15 days; as the rainy season approaches, gradually increase the number of irrigations, and spray the tree canopy once every 7-10 days to increase air humidity in the orchard, moisten the fruit rind, enhance the rind's adaptability to continuous rainy and high-temperature environments, and prevent fruit cracking; before the fruit is about to mature, stop watering.
6. Reasonable fertilization. When fertilizing pomegranate trees, organic fertilizer should be the main type, with sufficient phosphorus and potassium fertilizer applied according to a formula, and nitrogen fertilizer applied as little as possible. During the fruit expansion stage, foliar spraying with 0.3% potassium dihydrogen phosphate solution or 0.5% calcium chloride solution helps enhance rind toughness and prevent fruit cracking.
7. Reasonable chemical control. In the middle and late stages of pomegranate fruit development, spraying the fruit surface with a 25 mg/L gibberellin solution can reduce fruit cracking by 30%. In addition, applying adhesive tape strips soaked in 10-30 mg/L gibberellin solution to the calyx depression of pomegranate fruit, or spraying 0.3% paclobutrazol solution or 20-25 mg/kg ethephon solution, also has the effect of reducing or preventing fruit cracking.
8. Fruit bagging. This is generally carried out at the young fruit stage and has the effects of disease prevention, insect prevention, and fruit cracking prevention. Bagging has a certain buffering effect on drastic changes in temperature and humidity, can protect the fruit rind, reduce sunburn damage to the rind during dry periods and damage to fruit rind toughness from continuous high humidity, thereby preventing fruit cracking.
In addition, fruit-boring pests should be controlled in a timely manner.