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Foliar Spray in Vegetables, Fruits, and Field Crops: A Comprehensive Overview

 

Foliar spray is a vital technique in modern agriculture, used across a wide range of crops including vegetables, fruits, and field crops. It involves applying liquid fertilizers, micronutrients, growth regulators, or pesticides directly to the leaves of plants. This method provides rapid nutrient absorption and plays an essential role in enhancing crop yield, correcting nutrient deficiencies, and protecting against pests and diseases.





1. What Is Foliar Spray?

Foliar spray is the process of spraying nutrient solutions or agrochemicals onto the foliage (leaves) of plants. Unlike soil fertilization, where nutrients are absorbed through the roots, foliar application allows nutrients to be absorbed directly through the stomata and epidermis of the leaf surface. This method is particularly effective when root uptake is hindered due to poor soil conditions, drought, or root damage.




2. Importance and Benefits

  • Rapid Nutrient Uptake: Nutrients sprayed on leaves can be absorbed and translocated throughout the plant in a matter of hours.
  • Correcting Micronutrient Deficiencies: Essential trace elements like zinc, iron, manganese, and boron are often deficient in soil and can be effectively supplemented through foliar spray.
  • Enhanced Crop Yield and Quality: By promoting balanced nutrition, foliar feeding improves flowering, fruit setting, and overall crop quality.
  • Reduced Environmental Impact: Lower doses of fertilizers are needed compared to soil applications, minimizing leaching and environmental pollution.
  • Emergency Nutrition: During stress conditions like drought, cold, or high soil pH, foliar spraying provides a quick way to restore plant health.

3. Applications in Different Crop Categories

A. Vegetables (e.g., tomato, cabbage, spinach, peppers)

  • Common Foliar Nutrients: Nitrogen, potassium, magnesium, calcium, and micronutrients (Zn, B, Fe).
  • Growth Stages for Application:
    • Early vegetative stage for vigorous growth
    • Pre-flowering and fruit development stages for yield enhancement
  • Benefits:
    • Increases leaf chlorophyll content
    • Promotes uniform flowering
    • Enhances resistance to common pests and diseases


B. Fruits (e.g., mango, apple, citrus, grapes)

  • Foliar Sprays Used:
    • Calcium nitrate (to prevent fruit cracking)
    • Boron and zinc (for fruit set and sweetness)
    • Pesticides and fungicides for pest control (e.g., neem oil, copper-based fungicides)
  • Critical Timing:
    • Pre-flowering to improve pollination and fruit setting
    • Fruit enlargement stage to ensure uniform size and color
  • Outcomes:
    • Improved fruit quality and shelf life
    • Reduced physiological disorders like blossom-end rot and fruit drop

C. Field Crops (e.g., wheat, rice, maize, soybean)

  • Key Nutrients:
    • Urea (low concentration) for nitrogen boost
    • Micronutrients (especially iron and zinc for cereals)
  • Foliar Growth Regulators:
    • Cytokinins and gibberellins to improve tillering and grain filling
  • Disease and Pest Management:
    • Fungicides (e.g., mancozeb, propiconazole) and insecticides (e.g., neem-based, synthetic pyrethroids)
  • Effects:
    • Increases grain weight and number
    • Enhances plant resilience under stress (e.g., waterlogging or drought)


4. Best Practices for Effective Foliar Spray

  • Right Time of Day: Early morning or late afternoon when temperatures are cooler and stomata are open.
  • Correct Concentration: Over-concentrated solutions can cause leaf burn; always follow manufacturer guidelines.
  • Proper Equipment: Use fine mist sprayers for even coverage.
  • pH and Water Quality: Optimal pH for foliar solutions is 5.5–6.5; avoid hard or alkaline water.
  • Adjuvants: Surfactants can improve adherence and penetration of nutrients.


5. Limitations and Considerations

  • Temporary Effect: Foliar sprays are not a replacement for good soil nutrition.
  • Weather Dependency: Rainfall shortly after spraying can wash off nutrients.
  • Phytotoxicity: Excessive concentration or spraying under hot sun can damage leaves.
  • Limited Uptake of Macronutrients: While effective for micronutrients, foliar spraying is less suitable for supplying large amounts of N, P, or K.

Conclusion

Foliar spraying is a highly efficient and versatile tool in crop management, offering quick results and targeted delivery of nutrients and protective agents. When used judiciously in vegetables, fruits, and field crops, it enhances plant health, boosts productivity, and contributes to sustainable agriculture. By integrating foliar applications into standard crop production practices, farmers can address immediate nutrient deficiencies, improve crop resilience, and ensure better returns on investment.

Author:  Dr.P.Suseela, Former Professor & PI, Hi-Tech Research and 

Training Unit, Kerala Agrl. Uty and Consultant and Trainer of Hi-Tech cultivation

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