Controlling Flower Drop in Mango

Understanding Natural vs. Abnormal Drop

It's important to know that mango trees naturally shed a large percentage of their flowers, sometimes up to 99%. This is because many flowers are male, and even perfect flowers (which have both male and female parts) compete for resources. Abnormal drop occurs when environmental stress, pests, or diseases cause an even higher loss than usual, impacting your potential yield.

• Natural Drop: Occurs due to the high number of male flowers and competition among perfect flowers for limited resources.

• Abnormal Drop: Caused by external factors like extreme weather, water stress, nutrient deficiencies, or pest/disease attacks.

Key Factors Causing Excessive Flower Drop

Several factors can lead to more flower drop than is natural. Identifying these can help you take corrective actions.

Environmental Stress

• Temperature Fluctuations: Sudden changes, very high (above 38°C) or very low (below 10°C) temperatures during flowering.

• Humidity: Very low humidity can dry out flowers.

• Strong Winds: Can physically damage and dislodge flowers.

• Frost: Can severely damage delicate flowers.

Water Management

• Water Stress: Both too little and too much water during the flowering period can cause stress and flower drop.

Nutritional Imbalances

• Deficiencies: Lack of essential micronutrients like Boron and Zinc, or macronutrients like Phosphorus.

• Excess Nitrogen: Too much nitrogen can promote vegetative growth at the expense of flowering and fruit set.

Pests and Diseases

• Pests: Mango hoppers, thrips, and flower midges can directly damage flowers.

• Diseases: Powdery mildew and anthracnose are common fungal diseases that attack flowers.

Best Practices for Flower Retention

Implementing these practices can significantly reduce abnormal flower drop and promote better fruit set.

Water Management During Flowering

Ensure consistent and adequate moisture in the soil, but avoid waterlogging. The period from flower bud emergence to fruit set is critical.

• Pre-flowering: Reduce irrigation slightly to induce flowering.

• During Flowering: Provide light, regular irrigation. Avoid heavy watering that can cause waterlogging or sudden stress. Drip irrigation is ideal.

Nutrient Management

Balanced nutrition is key. Apply nutrients based on soil test results.

NutrientTimingApplication Method & Rate (Approx.)Phosphorus (P)Pre-flowering (2-3 months before)500-700g Super Phosphate per mature treePotassium (K)Pre-flowering (2-3 months before)300-500g Muriate of Potash per mature treeBoron (B)Just before floweringFoliar spray: 0.1-0.2% Borax solution (1-2g/L water)Zinc (Zn)Just before floweringFoliar spray: 0.2-0.3% Zinc Sulphate solution (2-3g/L water)

Note: Adjust rates based on tree age, size, and soil test recommendations.

Pest and Disease Control

Regular monitoring and timely intervention are crucial.

• Mango Hoppers: Spray insecticides like Imidacloprid or Thiamethoxam at the panicle emergence stage.

• Powdery Mildew: Apply fungicides such as Sulphur (wettable powder) or Hexaconazole at panicle emergence and repeat if needed.

• Anthracnose: Use systemic fungicides like Carbendazim or Propiconazole, especially in humid conditions.

Use of Plant Growth Regulators (PGRs)

Some PGRs can help reduce flower drop. Naphthalene Acetic Acid (NAA) is commonly used.

• NAA: Spray NAA at 10-20 ppm (parts per million) concentration when flowers are fully open. This can help reduce flower and young fruit drop. Consult with local agricultural experts for precise dosage and timing for your specific mango variety.

Other Cultural Practices

• Windbreaks: Plant tall trees around the orchard to protect from strong winds.

• Pollination: Encourage natural pollinators like bees. Avoid spraying insecticides during peak flowering hours.

By carefully managing water, providing balanced nutrition, controlling pests and diseases, and considering growth regulators, farmers can significantly reduce flower drop in mango trees. This integrated approach leads to healthier trees, more successful fruit set, and ultimately, a better yield.