Controlling Pink Borer in Maize

Identifying Pink Borer and Its Damage

The pink borer larva is pinkish-white with a dark head, growing up to 2.5-3 cm long. Adult moths are straw-coloured. Damage is most severe during the early stages of maize growth, typically 2-6 weeks after sowing.

• Larvae bore into the central shoot, causing the 'dead heart' symptom where the central whorl withers and dries up.
• Small holes can be seen on the stem where larvae have entered.
• In older plants, they bore into the stalk, weakening it and sometimes causing the plant to lodge (fall over).
• Feeding inside the cob can also occur, reducing grain quality and quantity.

Cultural Practices for Control

Simple farm practices can significantly reduce pink borer populations and prevent severe infestations.

• Timely Sowing: Sow maize early in the season to avoid the peak activity period of the pest.
• Field Sanitation: Collect and destroy all plant residues, including stubble and infested plants, immediately after harvest. This removes overwintering larvae and pupae.
• Crop Rotation: Rotate maize with non-host crops like legumes (e.g., groundnut, soybean) to break the pest's life cycle.
• Intercropping: Intercropping maize with certain legumes like cowpea or green gram can sometimes deter pests or attract their natural enemies.
• Balanced Fertilization: Avoid excessive nitrogen application, as high nitrogen levels can make plants more attractive to borers.
• Deep Ploughing: Plough fields deeply after harvest to expose pupae and larvae to predators and harsh weather conditions, reducing their survival.

Harnessing Natural Enemies

Encouraging and releasing natural enemies can play a vital role in managing pink borer populations biologically.

• Parasitoids: Release Trichogramma chilonis egg parasitoids at a rate of 50,000-100,000 per acre. Make 3-4 releases at weekly intervals, starting from 10-15 days after sowing, to target the borer eggs.
• Predators: Maintain biodiversity in and around the maize field to attract general predators like birds, spiders, and predatory insects that feed on borer larvae and moths.

Chemical Management Options

Chemical control should be considered when infestation levels are high and other methods are not sufficient. Always follow label instructions carefully and observe safety precautions.

• Granular Insecticides: For early infestations, apply granular insecticides like Carbofuran 3G or Phorate 10G in the leaf whorls at a rate of 8-10 kg per acre, 10-15 days after sowing. This targets young larvae effectively.
• Sprayable Insecticides: For older plants or severe infestations, spray insecticides such as Chlorantraniliprole 18.5% SC (4 ml per 10 litres of water) or Emamectin Benzoate 5% SG (10 grams per 15 litres of water). Ensure thorough coverage, especially targeting the plant whorl where larvae feed.
• Timing: Apply insecticides when the first signs of 'dead heart' appear or when 5-10% of plants show damage.

Integrated Approach for Sustainable Control

The most effective and sustainable strategy for pink borer control is Integrated Pest Management (IPM), which combines various methods.

• Monitoring: Regularly scout your fields for signs of damage and the presence of pink borer larvae or moths. Early detection allows for timely intervention.
• Thresholds: Apply interventions only when pest populations or damage levels reach economic thresholds, avoiding unnecessary pesticide use.
• Combination: Combine cultural practices, biological agents, and judicious, targeted use of chemical pesticides for comprehensive control.
• Resistant Varieties: If available in your region, consider planting maize varieties known to be tolerant or resistant to pink borer.

Controlling pink borer in maize requires a proactive and integrated approach. By combining good cultural practices, encouraging natural enemies, and using targeted chemical treatments when necessary, farmers can effectively reduce damage and protect their maize yields. Regular monitoring is crucial for timely and effective intervention.