Paddy or Rice is an important staple food for over half of the world’s population. It is grown in various environments but requires careful management for a successful harvest. The stem borer, also known as Scirpophaga incertulas or Rice Yellow Stem Borer, is a major pest that causes significant damage to paddy crops in many countries, including India, China, and the Philippines. Let’s check out more information on Stem Borer management in paddy below.
The larvae of the stem borer eat away at the stem of the paddy plant, which weakens the stem and causes it to break. The adult moth does not cause damage, but multiple generations per year can lead to significant crop loss. Effective management is crucial to minimize damage and ensure a successful harvest.
Stem borer management in Paddy
The life cycle of Stem Borer
Stem borers have eggs, caterpillars, pupae, and moths. Female moths lay eggs on both sides of host plant leaves. Caterpillars hatch after 4–7 days. Female moths lay 400–600 eggs in 2–3 clusters on rice plant leaves. Eggs hatch after 5-8 days. Young larvae fall to the ground, burrow into stems or leaves, and devour green sections. They grow to 20 mm by burrowing into the stem and eating the interior tissues. Pupae survive 6–10 days and have a thin silken case. Adult moths have the great flying ability but die two to three days after laying eggs.
How does Stem borer attack Rice crops?
The larvae descend to the plant’s surface, penetrate the stem or leaf sheath, and feed on the green tissues. They then eat the inner tissues as they burrow into the stem, growing to a full-grown size of 20 mm. If the infestation is bad, this feeding could weaken the stem and make it harder for the plant to take in nutrients and water, leading to lower yields or even death.
Identification of Stem Borer
- Eggs: The stem borer sporadically lays its small, flat, oval, brown eggs, typically near the base of plants.
- Larvae: Use a small, sharp knife to make a longitudinal cut in a stem to reveal the larvae. An inch-long bug with a brown head and a plump, white, wrinkled body will be visible.
- Adult: The adult stem borer, also known as the bhirud, is approximately 12 inches long and resembles a moth. With a black body and orange-red stripes, it resembles a wasp. Its front wings are metallic green, while its back wings are translucent.
Damage symptoms of Stem Borer in rice
The larval stage of the stem borer moth, which feeds on the internal tissues of rice plants, is the most destructive.
- Yellowing and wilting: Stem borer damage begins with leaf yellowing and wilting. The larvae penetrate the stem and eat the inner tissues, preventing the plant from absorbing water and nutrients.
- Boreholes: Larvae feed through stem boreholes. Stem borer infestation may cause this.
- Dead heart: The plant’s growing tip dies. Larvae eat the stem’s interior tissues, preventing growth.
- Lodging: The plant falls over as the stem bends and weakens. Larvae have weakened the stem. Stem borer infection can lower rice crop yields. Because larvae destroy the stem, the plant can’t absorb water and nutrients, decreasing growth and grain output.
- Frass: Larvae excrete frass when feeding. It indicates stem borer infestation on the plant or ground.
- Plant death: Stem collapse. The larvae weaken the stem, which collapses.
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Paddy crop cycle at which attack by Stem Borer occurs.
Dead hearts appear before flowering, and white heads or white ears appear after flowering due to damage caused by larvae feeding inside the stem and cutting the vascular system.
Factors that promote Stem Borer population in paddy crop
High nitrogen, soil silica deficiency, cold, dry weather with high humidity and low temperature, and crop stubble all helped pests survive in different environments.
Cultural control of Stem Borer in paddy crop
- Cutting off the tips of seedlings before transplanting.
- Cultivating resistant Crop varieties.
- Gathering and destroying egg masses.
- Avoiding close planting and prolonged water stagnation in the early stages.
- Removing and destroying affected tillers,
- Borers will be less of a problem in the next crop if the stubble is taken out and thrown away correctly.
- Harvesting the crop up to the ground level and disturbing stubbles with a plow right after harvest are all best practices.
Biological control of Stem Borer in paddy field
- Trichogramma japonicum egg parasitoids were released thrice a week, starting 28 days after the transplant, at a rate of 5 ccs (1 million egg parasitoids) per hectare per release.
- To minimize oviposition by the stem borer, Bacillus thuringiensis var kurstaki can be administered at a rate of 2.5 kg/ha.
- In the morning, egg cards should be released in the field and fastened under the leaf surface facing out.
- Chemical sprays should be avoided three days before and seven days after the release of egg card fields.
- Natural enemies include the wasp Tetrastichus schoenobii, and the wasp Telomomous rowani are used for biological control.
Chemical control of Stem Borer in rice crop
- Insecticides such as carbofuran, chlorpyriphos, and quinolphos are commonly used.
- Apply 16.5 kg of Basudin 10G/Furadan 3G/Diginol 146 per hectare.
- Apply 344 mL of Dimecron/Bennicron/Pillarcron 100 SL per acre.
- To control this pest, spray Carbofuron, monocrotophos 36 EC diluted in 500-700 liters of water. Spray the solution on fields with three to four centimeters of standing water.
- Virtako has successfully reduced stem borers while increasing plant vitality and quality.
- Stem borers can be managed with granular insecticides like Cover at a rate of 4 kg/acre.
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Organic/natural control of Stem Borer in rice fields
- One light trap/5 hectare attracts and kills moths.
- Perch birds attract predators.
- Sex pheromone capture rice stem borer.
- Pheromone traps (10–12/ha) provide timely control. Change lures every 15-20 days.
Conclusion
A combination of cultural approaches, biological management utilizing egg parasitoids, and chemical treatments, including Bacillus thuringiensis and pesticides, can effectively control stem borer pests. Early diagnosis and treatment are critical for reducing crop damage and increasing yields.
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