Top borer is a common sugarcane pest that causes significant crop damage. Borer is a member of the Noctuidae family, and sugarcane is primarily affected by Scirpophaga excerptalis. These borers cause harm to sugarcane plants by tunneling into the stalks and feeding on the internal tissues, which can result in wilting and stunted plant development. It is essential to effectively manage top borers to minimize crop losses and maintain high yields.
Top Borer Management in Sugarcane
Life Cycle of Top Borer
The life cycle of a Top Borer takes complete metamorphosis from egg to larva, pupa, and adult. Female top borer moths lay 10-80 eggs per mass on top leaves’ undersides. Buff-colored hairs shield these clusters from predators. The eggs hatch into tiny, smooth, white, or cream-colored larvae with red mid-dorsal lines and yellow heads. The larvae ate the host plant’s stem tissues, lowering its vigor and yield.
Larvae grow and change color over 25-30 days in six instars. Fully grown larvae build a pupal cavity in the stem and pupate for 6-21 days before becoming adults. The caterpillar makes a hole in the pupal chamber for the adult moth to flee. The top adult borer is a white moth with a 25-30 mm wingspan and a buff-colored anal tuft in the female’s abdomen tip. Adults leave the pupal tube at night and live for 2-3 days. Adults do not eat and focus on mating and laying eggs to restart the cycle.
Factors Favoring Growth/ Causes or Identification of Top Borer Spread in the Field
- The adult moth has silvery-white wings with feathered tips and the female deposits eggs with yellow-brown hairs or tufts.
- The larvae tunnel through folded leaves, damaging the midrib of the plant and decreasing its yield potential. The larvae are approximately 35 mm long, with a creamy white or yellow body, a brown head without stripes, and atrophied appendages.
- The third generation causes the most damage to sugarcane, and immature plants are especially susceptible in humid environments.
- Low soil fertility, plant damage or stress, using contaminated planting material, and the proximity of infected fields can also contribute to the spread of the top borer.
Damage Symptoms of Top Borer in Sugarcane
- The top borer, known scientifically as Scirpophaga excerptalis, causes severe devastation to sugarcane crops.
- The symptoms of damage caused by the top borer in sugarcane include the appearance of hearts that have died after six months of growth and are difficult to remove.
- Additionally, parallel rows of shot holes are visible in the emerging leaves, and boreholes at the tip of the shoot can give the cane the appearance of a clumped top.
- Borer predominantly targets the apex of the canes, boring through the growing point and upper joints until they reach the sappy portion of the stem, where they feed on the tissues and destroy the cane.
- Top borers also mine their way to the base by boring into the unfolded leaves, preferably the midrib. The feeding activity of caterpillars frequently causes a reduction in cane diameter, restricted growth, and early crop maturity.