Fennel (saunf) is an important spice crop grown widely in Rajasthan, Gujarat, and parts of North India. The crop is valued for its aroma, flavour, and medicinal properties. However, fennel is highly sensitive to pests, especially thrips. Thrips are tiny insects that suck sap from young leaves, flowers, and tender shoots. If not controlled in time, they can cause major yield losses. Here is an easy-to-understand guide for farmers on identifying and managing the thrips problem in fennel crops.
1. How to Identify Thrips in Fennel
Thrips are very small—usually just 1–2 mm long—and difficult to see with the naked eye. They are slender, yellowish or brownish insects. Farmers should look for:
Silvery patches or streaks on leaves
Curling or drying of leaf tips
Flowers becoming deformed
Sticky droplets (honeydew) on leaves
Presence of black dots (thrips waste)
When thrips attack heavily, the crop looks pale, weak, and loses aroma.
2. Why Thrips Spread in Fennel
Thrips multiply quickly in certain weather conditions:
Hot and dry climates
Low humidity
Excess nitrogen fertilizer
Monocrop fields without crop rotation
Wind also helps thrips move from one field to another.
3. Cultural Practices to Reduce Thrips
Good field management reduces thrips pressure even before spraying is needed.
Avoid excess nitrogen:
Too much urea makes the crop more tender and attractive to thrips. Balanced fertilization is important.
Use crop rotation:
Rotating fennel with crops like mustard, cumin, or wheat reduces thrips population buildup in the soil.
Maintain proper spacing:
Crowded plants create favourable conditions for thrips. Adequate spacing improves air movement and reduces pest spread.
Remove infested weeds:
Weeds like wild fennel or Amaranthus act as hosts for thrips. Keeping field borders clean helps limit pest movement.
4. Irrigation Management
Thrips cannot tolerate high humidity. Light irrigation or sprinkling water can reduce their activity. During severe infestation, farmers can sprinkle water on the crop in the morning to dislodge many thrips.
5. Use Organic and Bio-Control Methods
Farmers who prefer natural methods can use:
• Neem Oil Spray:
Mix 3–5 ml neem oil per litre of water and spray thoroughly under the leaves. Neem reduces feeding and reproduction.
• NSKE (Neem Seed Kernel Extract 5%)
This is effective in early infestations and safe for beneficial insects.
• Beauveria bassiana
This entomopathogenic fungus infects thrips naturally.
• Verticillium lecanii
Works well under slightly humid conditions and controls sucking pests.
Organic sprays may need to be repeated every 7–10 days for best results.
6. Chemical Control for Severe Infestation
When thrips population becomes high, chemical sprays may be necessary. Farmers should use recommended insecticides and follow correct dosages. Spraying should be done:
During early morning or evening
Using a fine nozzle to target the lower leaf surface
Avoiding repeated use of the same chemical to prevent resistance
Always ensure proper safety measures during chemical application.
7. Avoid Surfactants or Harsh Chemicals
Fennel leaves are sensitive. Strong chemicals or mixing multiple pesticides can burn leaves and reduce crop quality. Stick to recommended solutions only.
