Control of Stem Borer in Wheat
Stem borer is one of the serious insect pests that can damage the wheat crop and reduce yield if not managed properly. Though wheat is a hardy crop, pest attacks like stem borer can cause significant loss, especially in areas where the weather remains warm and humid during the crop’s growth period. Understanding how to identify, prevent, and control stem borer helps farmers protect their wheat fields and achieve better production.
1. Understanding the Stem Borer Problem
The stem borer that affects wheat is commonly known as the pink stem borer (Sesamia inferens). It is the same pest that also attacks other crops such as rice, maize, and sorghum. The pest is more active in regions where wheat follows a rice crop, as the larvae can survive on rice stubbles and then move to wheat.
The larvae of the stem borer are pinkish-white in color and bore into the stem of young wheat plants. Once inside, they feed on the inner tissues, cutting off the flow of nutrients. This leads to dead central shoots, known as “dead hearts” in young plants, or “white ears” during grain formation. Such plants do not produce grains, leading to reduced yield and patchy fields.
2. Symptoms of Damage
Central shoots of young wheat plants dry up, forming dead hearts.
In later stages, the ear heads appear white and do not bear grains.
Affected stems may have small holes or frass (sawdust-like material) near the base.
The crop shows uneven growth and reduced tillering.
Identifying these symptoms early helps farmers take quick control measures before the pest spreads.
3. Preventive Measures
Prevention is always better than cure when it comes to stem borer control. Farmers can follow these simple preventive steps:
Crop rotation: Avoid sowing wheat immediately after rice in the same field. Rotating with non-host crops like pulses or oilseeds helps break the pest life cycle.
Field sanitation: Remove and destroy rice stubbles and other crop residues that can harbor the pest.
Timely sowing: Early sowing of wheat (in November) can help the crop escape severe infestation, as stem borer activity increases in late winter.
Proper irrigation and nutrition: A well-nourished crop is more resistant to pest attacks. Avoid waterlogging, as it favors pest development.
4. Mechanical and Biological Control
Clipping and destruction: Remove and destroy infested shoots and white ears to reduce pest population.
Light traps: Installing light traps in and around the field during the early crop stage can attract and kill adult moths.
Natural enemies: Encourage beneficial insects like Trichogramma wasps that parasitize the eggs of stem borers.
5. Chemical Control
If the infestation becomes severe, chemical control may be needed. Spraying or dusting should be done at the right stage for best results.
Apply chlorpyrifos 20% EC (2.5 ml per litre of water) or quinalphos 25% EC (2 ml per litre of water) uniformly on the crop, especially near the base of plants.
Another option is to use carbofuran 3G granules at the time of sowing, mixed with soil, to prevent early infestation.
Always follow label instructions and safety precautions while handling pesticides. Avoid overuse to protect beneficial insects and the environment.
6. Conclusion
Stem borer in wheat can cause serious yield losses if ignored. Farmers should focus on integrated pest management (IPM)—a combination of field hygiene, crop rotation, use of light traps, biological control, and need-based chemical application. Early detection and timely action are the keys to successful control. By following these steps, farmers can ensure a healthy wheat crop with higher productivity and better grain quality.
