Based on research, apples may reduce the risk of colon, prostate, and lung cancer. Apple fiber also prevents heart disease and controls weight and cholesterol levels by preventing fiber reabsorption.
In Indonesia, which has a tropical climate, several apple varieties have good adaptations to highlands/mountains with cold temperatures. In addition to cold temperatures, the planting place for apples should have a dry climate or an annual rainfall of 1,000 – 2,500 mm with solar radiation of 50-60% per day and a humidity of 75-85%. If the rain is heavy and falls at the same time as the flowering period, the flowers will not turn into fruit. Although apples can grow in different soil types namely Regosol (Entisol), Andosol (Andisol), and Latosol (Inceptisol), the ideal soil characteristics are medium texture, loose consistency, effective depth >50cm, good drainage, and soil pH 5, 5 – 7
Rome Beauty, Manalagi, and Ana are the most commonly grown apple varieties in Indonesia. Characteristics of Rome Beauty apples include greenish-red skin, slightly rounded, slightly hard flesh, a strong aroma, and a slightly sour taste. The skin of the Manalagi apple is greenish-yellow, slightly rounded, tastes sweet, has a fragrant aroma, and the water content is slightly lower. While the shape of the Ana apple is oval, the skin is red and thin, and the flesh is soft and tastes tart.
Compared to the Rome Beauty and Manalagi varieties, the Ana variety is better planted in a higher place. The characteristics of a good apple seed are increased by grafting, the rootstock and shoot are straight and healthy, the roots are thick, the leaves are fertile and healthy, and 6 months or older from the time of grafting and certification.
Hole preparation and planting
To be able to plant at the beginning of the rainy season, it is necessary to clear the land, create terraces (slopes) and plant holes during the dry season. The recommended hole sizes are length, width, and depth of 60 cm each. The spacing for the Manalagi variety is 3-3.5m x 3.5m, while for Ana and Rome Beauty it is 2-3m x 2.5-3m.
To improve the fertility of the root area, dark-colored topsoil is loosely mixed with 20 kg of organic matter (liquid manure) and 0.5 kg of dolomite or natural phosphate if the soil reaction is acidic (pH < 5.5). Before the rain, the soil mixture is placed in the hole and incubated for at least 2 weeks.
The beginning of the rainy season is an ideal time for planting as the availability of water and air temperature aids in seed adjustment in the field. Planting is done by placing seeds in holes and the roots must be arranged so that they spread in all directions. The roots are then covered with soil up to the level of the root collar and compacted so that the plant stands upright and does not collapse easily. To withstand strong winds, each plant must be loosely staked and tied.
In addition to the formation of a crown structure, branch bending should promote the emergence of generative shoots on side branches. This activity is carried out after the plants have adapted to the field and have fairly long and strongly curved branches, usually around 1-2 cm in diameter. The trick is that 3-4 branches are bent horizontally and tied with a rope that is stuck in the ground. Next, the leaves are threshed (dirompes) and the ends of the branches are cut off.
At least apple plants need macronutrients (C, H, O, N, P, K, Ca, Mg and S) and micronutrients (Fe, Zn, Mn, Cu, B, Mo). The main sources of macronutrients are chemical fertilizers, while the sources of micronutrients are organic materials and chemical fertilizers.
The macronutrients N, P, and K are used by plants primarily for the formation of vegetative and generative organs and are therefore required in large quantities. To meet the needs of these three elements, plants must receive additional chemical fertilizers in a balanced way, applied regularly every 2-3 months.
To maintain soil looseness and take up micronutrients/other elements, it is recommended to add 20-40kg/tree of organic matter and lime when the soil pH is <5.5 at the end of each dry season.
In Indonesia, where there is not a long cold spell, treatment of perommis (artificial defoliation) combined with branch bending and end pruning can break the generative shoots, particularly the side shoots, followed by the release of flowers. Ideally, leaf change occurs when the generative shoots are established, usually around 2 weeks after harvest.
Leaf perommes can be done manually or by spraying old leaves (burning leaves) with a growth regulator containing the active ingredient Hydrogen Cyanamide with 10% Urea. As a rule, leaf outings in April and October give better results than other months because the flowers are protected from rain.
Appropriate thinning of apples can improve crop quality and maintain production stability. This activity is carried out by reducing the number of fruits that are in clusters, leaving 2-3 fruits that are uniform in clusters. This activity should be done when the fruit is 8-9 weeks post-flowering.
Especially for Manalagi apples, when the fruit is about 3 months old after flowering, it needs to be wrapped in clean and waterproof paper. Unwrapped, the part of the fruit that is exposed to direct sunlight turns reddish and the other part remains greenish-yellow, making its appearance less attractive. This activity is performed after fruit thinning or 3 months after leaf budding.
Main pests and diseases
During its growth, many types of pests and diseases affect apple plants. After the leaves are dirompes up to the next 3 months is a critical time for pest and disease attacks. Some of the pests that frequently attack are aphids, scale insects, mites, trips, and caterpillars. While the main diseases are powdery mildew and Marsonina coronaria.
Examples of active pesticide ingredients commonly used to control these pests are imidacloprid, abamectin (aphids, scale insects, tripes), dicofol, piridaben (mites), and cypermethrin (worms), among others. Drugs commonly used to combat disease include difenokonazo, propineb, mankozeb, and others.
Unlike apples in the subtropics, treating the branch bend with Perommis leaves makes apples in Indonesia ready for harvest twice a year. Rome Beauty apples can be harvested when the fruit is around 120-140 days old, Manalagi around 115, and Ana around 100 days after flowering.
Harvest should be done in the morning in sunny weather. The picked fruits must be carefully placed in baskets lined with plastic bags to avoid damage to the harvested fruits.