Growth Patterns and Fertilization Requirements of Apple Trees

I. Fertilization Characteristics of Apple Trees at Different Ages

Young trees (1–3) year) During the vegetative growth phase, which is critical for the development of the tree canopy and root system, nitrogen fertilizer should be the primary nutrient to ensure normal tree growth; appropriate applications of phosphorus and potassium fertilizers will promote shoot maturation, helping the trees overwinter safely.

Early fruiting stage (4–6) year) As fruit trees transition from vegetative to reproductive growth, fertilization should prioritize phosphorus and potassium, supplemented with micronutrients, while nitrogen application is kept at an appropriate level.

Peak fruiting period (6 years or more) Fruit trees primarily focus on fruit production, consume substantial nutrients, and therefore require ample fertilization with a complete and balanced nutrient profile.

II. Growth Patterns and Fertilization Requirements of Fruit Trees

1. The root system of apple trees exhibits three growth peaks; the first occurs before bud break, characterized by abundant root emergence but a relatively short duration, relying on stored nutrients from the previous year. If fertilization was insufficient the prior year, apply an additional nitrogen fertilizer, supplemented with phosphorus, potassium, and micronutrients. As flowering and new shoot growth commence, root activity declines to a low level.

2. From the time new shoot growth is about to cease until just before fruit enlargement accelerates and flower bud differentiation begins (late June to early July), the roots experience a second peak in growth. During this period, abundant foliage and strong photosynthetic activity produce ample nutrients, promoting rapid root development; roots grow vigorously and for an extended duration, making this the phase with the highest annual root production. As fruits enlarge, flower buds differentiate, and autumn shoots begin to grow, aboveground nutrient consumption increases, causing root growth to decline once again. At this stage, it is advisable to apply phosphorus and potassium fertilizers, supplemented with nitrogen and micronutrient fertilizers, to ensure proper flower bud differentiation and lay the foundation for a high yield in the first year.

3. After fruit harvest, as nutrients are remobilized from the leaves to the roots, root growth experiences a third peak. This peak lasts longer but is relatively weak; when soil temperatures approach 0°C, root activity ceases and the roots enter dormancy. At this stage, apply a sufficient amount of organic base fertilizer, along with a heavy dose of nitrogen fertilizer and a balanced application of phosphorus fertilizer. During August and September, with ample sunlight and favorable soil moisture, applying base fertilizer promotes the development of new roots, restores tree vigor, enhances the trees’ cold and drought resistance, and reduces flower and fruit drop in the following spring.

4. Apply micronutrients appropriately. Micronutrients play an indispensable role in tree growth and development, as well as in achieving high quality and high yields. When their supply is insufficient, deficiency symptoms may arise: iron deficiency causes chlorosis, zinc deficiency leads to small‑leaf disease, and calcium deficiency results in bitter pit and fruit cracking, among other issues.