Maize, also known as corn, is one of the major cereal crops grown in India for food, fodder, and industrial use. It grows well in both kharif and rabi seasons, but like any other crop, it is affected by several insect pests. Among them, stem borer is the most common and destructive pest that causes serious damage to maize plants. Farmers often lose a large part of their yield if the pest is not managed properly. Let us understand how to identify, prevent, and control stem borer in maize.
1. About the Stem Borer Pest
The maize stem borer, mainly Chilo partellus and Sesamia inferens, attacks the crop at different growth stages. The moths lay eggs on the lower surface of maize leaves. When the larvae hatch, they first feed on the leaf surface and then bore into the stem. Inside the stem, they eat the internal tissues, which blocks the movement of nutrients and water within the plant. As a result, the plant becomes weak, stunted, and produces fewer or no cobs.
2. Symptoms of Stem Borer Damage
Small holes or “window-like” patches on the leaves (early stage).
Presence of frass (insect waste) inside the leaf whorls.
Central leaves drying up while outer leaves remain green, forming a typical “dead heart” symptom.
Stems become hollow or broken.
Cobs are often small or poorly filled.
Early identification of these symptoms is important to start control measures in time.
3. Conditions Favoring the Pest
Stem borers thrive in warm and humid weather. The problem is more common during the rainy season and in areas where maize is continuously grown without crop rotation. Dense sowing, excessive nitrogen fertilizer, and late planting also increase the risk of infestation.
4. Integrated Management Practices
Managing stem borer requires a combination of preventive and control methods rather than depending only on chemical sprays. The following steps can help farmers control the pest effectively:
a. Field Sanitation and Crop Rotation
After harvest, remove and destroy stubble and infected plants because the larvae and pupae can survive inside the stems. Avoid growing maize continuously in the same field. Rotating maize with non-host crops like pulses or oilseeds breaks the pest life cycle.
b. Timely Sowing and Proper Spacing
Sow maize at the recommended time for your region. Early sowing helps the crop escape peak pest attack. Maintain proper plant spacing to allow good air movement, which reduces humidity and pest buildup.
c. Use of Resistant Varieties
Select maize varieties that are tolerant or resistant to stem borer, as recommended by agricultural universities or Krishi Vigyan Kendras (KVKs).
d. Biological Control
Encourage natural enemies like Trichogramma chilonis, a tiny wasp that parasitizes stem borer eggs. Releasing Trichogramma cards in the field at 10-day intervals during the early crop stage can reduce pest population naturally.
e. Chemical Control
If infestation is severe, apply insecticides such as chlorantraniliprole or carbofuran granules in the leaf whorl at the early stage of the crop, following recommended doses and safety instructions. Always avoid unnecessary spraying and rotate chemicals to prevent resistance.
f. Balanced Nutrition and Irrigation
Avoid excessive nitrogen, as it attracts pests. Apply fertilizers in balanced amounts and irrigate the crop at proper intervals to maintain plant vigor.
In conclusion, stem borer can be effectively managed through timely field sanitation, crop rotation, use of resistant varieties, biological control, and careful use of insecticides. Regular field inspection and early action are the keys to keeping maize crops healthy and ensuring good yields for farmers.
