The cherry fruit enlargement period is a critical stage in cherry growth, characterized by high nutrient demands. Selecting appropriate foliar fertilizers is essential to promote fruit expansion, enhance yield, and improve quality. Below are some commonly used foliar fertilizers and their effects:

1. Alginic Acid Fertilizer

1. Main Components: Derived from seaweed extracts, alginic acid fertilizer is rich in trace elements and organic matter, providing comprehensive nutrients for plants.
2. Mechanism: Regulates nutrient absorption, enhances stress resistance, promotes root development, and improves fruit quality and yield.
3. Application: Spray foliarly, adjusting dosage based on crop requirements and soil conditions.

2. Potassium Dihydrogen Phosphate (KH₂PO₄)

1. Main Components: A high-efficiency phosphorus-potassium compound that rapidly replenishes essential P and K.
2. Mechanism: Phosphorus strengthens root systems and photosynthesis, while potassium improves drought and disease resistance.
3. Application: Apply via foliar spraying, but avoid overuse to prevent leaf scorching.

3. Amino Acid Fertilizer

1. Main Components: Contains essential amino acids that support protein synthesis and stress/pest resistance.
2. Mechanism: Directly fuels plant growth and accelerates fruit enlargement.
3. Application: Spray foliarly, but avoid mixing with other fertilizers to prevent chemical reactions.

4. Humic Acid Fertilizer

1. Main Components: A natural organic fertilizer rich in humic substances and microbial compounds.
2. Mechanism: Improves soil structure, boosts beneficial microbes, and enhances water/nutrient retention.
3. Application: Apply basally, via furrows, or foliarly. Avoid excessive use to maintain soil ecological balance.

5. Microbial Inoculants

1. Main Components: Contains beneficial microorganisms like Bacillus subtilis and actinomycetes.
2. Mechanism: Improves soil health, strengthens stress/pest resistance, and stimulates growth and fruiting.
3. Application: Apply via seed coating, root dipping, or foliar spraying. Choose formulations suited to local crops and climates.

6. Trace Element Fertilizer

1. Main Components: Includes Fe, Zn, Cu, Mn, B, Mo, etc., which are vital for plant metabolism.
2. Mechanism: Supports biochemical reactions critical for growth and fruit enlargement.
3. Application: Select appropriate types and dosages based on crop needs and soil conditions. Use foliar spraying for optimal absorption.

When selecting foliar fertilizers, consider the cherry tree’s growth stage and soil conditions. Combine different fertilizers synergistically while adhering to the "small dosage, frequent application" principle to avoid phytotoxicity. Complement fertilization with practices like rational irrigation and pruning to maximize results.