Is the star apple suitable for growing in Shandong? A detailed guide to its cultivation techniques

The star apple, also known as the star apple and the milk fruit, originated in tropical America or the West Indies, and is abundantly produced in the Caribbean region. It was introduced into our country from Southeast Asia in the 1960s-1970s, and is distributed in Hainan, Guangdong, Taiwan, China, Fujian, Yunnan and other provinces. So what are the cultivation techniques for the star apple? Is it suitable for growing in Shandong?

1. Is the star apple suitable for growing in Shandong?

The star apple is a tropical fruit with strict requirements for year-round temperature and temperature differences. It can grow and flower and fruit normally in sandy soil with a pH of 6-7, organic matter content <1, an average annual temperature of 20-22°C, an average annual relative humidity of 70-80, an extreme winter low temperature of 3-5°C, and an average annual rainfall of 1400-1600 mm. Therefore, if planted in the open field, it is not very suitable for growing the star apple. Moreover, the star apple tree is tall, reaching up to 20 m in height, and is generally planted at 5-7 m tall, so it is also not suitable for greenhouse cultivation. Therefore, Shandong is not suitable for introducing the star apple.

2. What are the cultivation techniques for the star apple?

1. Propagation techniques: The star apple can be propagated by seeds, layering, cuttings, grafting and other methods. Seedlings grown from seed need 5-7 years to fruit, while layered and grafted seedlings can fruit 2-3 years after planting. The plant height of layered and grafted seedlings can be controlled within 3 m, so dwarfed cultivation is advisable in production.

2. Planting methods: For planting the star apple, choose gentle sloping land with loose, fertile soil, slightly acidic to neutral pH, and good drainage. The spacing between plants and rows is determined according to the purpose of cultivation and use: 4×5 m for economic cultivation, and more than 10 m for ornamental cultivation. The planting hole is 1×1×0.8 m, and 25-30 kg of farmyard manure is filled into each hole as base fertilizer. Generally, planting is done in the rainy season, and sufficient water is poured after planting to settle the roots.

3. Fertilizer and water management: Young star apple trees are given nitrogen fertilizer twice a year, 100-120 g each time; mature fruiting trees are given 1-1.5 kg of compound fertilizer per tree each year, applied in May and September respectively, which helps promote shoot growth and flowering and preserve and plump the fruit; in winter, 15-20 kg of organic fertilizer is applied per tree. Water regularly once a week, and pay attention to preventing waterlogging in the rainy season.

4. Pruning and shaping: The star apple has a low branching position and many dense branches, so attention should be paid to pruning and shaping. On young trees, first form 3-5 main branches, then gradually develop an open-center tree shape year by year. Diseased and pest-infested branches and crowding branches should be cut away in time to increase the fruit-setting rate.

5. Management during the fruiting period: To prevent fruit flies and bird damage, the fruits should be bagged starting from the young fruit stage. The fruits can be harvested once they are colored, but because fruits on the same tree do not ripen at the same time, they must be harvested in batches. When harvesting, cut at the fruit stalk to avoid mechanical damage to the fruit that would shorten the shelf life of the fresh fruit. After harvest, the fruit softens after ripening, and the quality and flavor are excellent.

6. Pest and disease control: The star apple has relatively mild pests and diseases. Common ones include fruit flies and fruit-boring insects damaging the fruit, and scale insects damaging the leaves. Measures such as fruit bagging combined with pruning and thinning branches to let in light can achieve a relatively good control effect.

3. Characteristics of the star apple

The star apple is a berry; when ripe, the skin is red and the flesh is pale yellow, and each fruit weighs 2-4 g, with a crisp, sweet taste and a delicate fragrance. In April, the tender shoots begin to elongate and set fruit; in July it begins to ripen, and it finishes ripening in December, with a fruit-viewing period as long as 6-8 months. A plant about 40 cm tall can set as many as a hundred fruits over time, and a large plant type more than 1 m tall can set as many as a thousand fruits over time. Seedlings planted in spring of the same year, or cuttings, can set fruit by autumn.

What is also peculiar about the star apple is that no matter whether you cut open a leaf, fruit or branch, it exudes a white milky sap like milk, which is the origin of the name “milk fruit”. The milk fruit has strong adaptability, is not choosy about soil, likes light and tolerates half shade, is cold-tolerant, and can withstand low temperatures of about -15°C; it has very few pests and diseases, extensive cultivation and management, and soft branches that are easy to shape, making it an excellent material for making bonsai.

The star apple is rich in nutrients, and its fat, protein and iron content is higher than that of fruits such as apples, pears and plums. Its sugar content is 13%. Its roots and fruits can be used medicinally, and can enrich the blood, promote lactation and astringe; it treats red and white dysentery, strangury and tumors, insufficient milk, nine-child rotten intestine, hemorrhoids, fatigue and weakness, jaundice, indigestion, malaria, lymphatic tuberculosis, leukorrhea, mastitis, bruises, sore waist and back pain and other conditions.