YELLOW STEM BORER IN PADDY

YELLOW STEM BORER IN PADDY

Telugu name: Kandam toluchu purugu

Scientific name: Scirpophaga incertulas

Identification of the pest:

Eggs: creamy white, flattened, oval and scale like and laid in mass and covered with buff coloured hairs

Larva: pale yellow with dark brown head

Pupa: White silken cocoon are found inside the stem

Adult:

Female moth: Bright yellowish brown; forewings with a black spot.

Male moth: Smaller with pale yellow; forewings without blackspot.

Lifecycle:

S. incertulas is monophagous on rice. The number of generations depends on environmental conditions, primarily temperature. The life cycle of YSB comprises of four stages i.e., egg, larva, pupa and adult stages. In cooler climates, diapause occurs in larval stage.

Adult lays eggs on leaf tips. Newly hatched larvae hang down with a silken thread and enters the stem at base, causing "Dead Heart", and/or "White ears", depending on when the damage occurs.

Symptoms:

  • Presence of brown coloured egg mass near leaf tip.
  • Larva bores into central shoot of paddy seedling and tiller, causing drying of the central shoot known as "dead heart".
  • If infestation occurs in grown up plant, the whole panicle becomes dried and known as "white ear".
  • Affected shoots and panicles could be easily pulled by hand

Favourable Conditions:

  • Fields planted later than surrounding fields.
  • Stubbles that remain in the field.

ETL: 10% Deadheart symptoms 

            2% White ear symptoms.

Management:

Cultural practices:

  • Clip the tip of the leaf blades before transplanting - The eggs of yellow stem borers are laid near the tip of the leaf blade. Clipping the seedling before transplanting reduces the transfer of eggs from the seed bed to the field.
  • Spray a neem seed kernel solution to repel the adult females and reduce the egg laying activity.
  • Plant all rice fields at a similar time as neighboring fields to avoid pest build-up.
  • Plant stem borer resistant varieties For example, IR36, IR32, IR66, and IR77 have varying degrees of resistance to some stem borer species.
  • Spread straw in the sun to kill resident stem borer larvae.
  • Plow and flood the field after harvest.

Biological control:

  • Release of egg parasitoid Trichogramma japonicum thrice at weekly interval starting 28 days after transplanting @ 5 cc (1 lakh egg.parasitoids)/ha/release followed by the release of Trichogramma japonicum at 35 and 42 DAT.
  • Apply Bacillus thuringiensis var kurstaki at 2.5 kg/ha to reduce the oviposition by the stem borer.
  • Release the egg cards in field during morning hours. The egg cards under the leaf surface facing outside.
  • Avoid spraying of chemicals on three days before and upto to seven days after field release of egg cards.

Trap methods:

  • Set up one light trap/5 ha to attract and kill the moths.
  • Set up bird perches to encourage bird predators.
  • Use sex pheromone trap for the control of rice stem borer.
  • Monitor through pheromone traps (@10 to 12/ha) for timely control measures. Change the lure at 15-20 days intervals.

Chemical control:

  • Chlorantraniliprole 18.5% SC: Mix 4 ml in 10 liters of water,Spray evenly on the field during the early infestation stage.
  • Fipronil 5% SC: Mix 2 ml in 1 liter of water,Apply during the early stages of pest attack.
  • Cartap Hydrochloride 4G: Use 10 kg per acre.Broadcast it in the field during standing water conditions.
  • Flubendiamide 39.35% SC: Mix 0.2 ml per liter of water,Spray thoroughly to cover the crop.
  • Apply chemicals in the evening for better results.
  • Use protective gear while spraying.
  • Follow the recommended dose and avoid overuse to prevent resistance.
  • Rotate chemicals to maintain effectiveness and protect beneficial insects.
  • For effective control of stem borer use Biopesticide “LARVEX”@250ml/acre.

Larvex_insectiicde

FAQs:

1. What is the yellow stem borer, and why is it harmful?

It’s a major pest in paddy fields, causing dead hearts and whiteheads, which reduce yield. Early identification is crucial.

2. How can I identify yellow stem borer damage?

Look for dead hearts (dry central shoots) in the vegetative stage and whiteheads (empty panicles) at maturity. Regular field scouting helps.

3. When does the yellow stem borer attack paddy?

They are most active during the tillering and panicle initiation stages, especially in warm, humid conditions.

4. How can I control yellow stem borers naturally?

Use pheromone traps, light traps, and natural predators like Trichogramma wasps to manage them effectively.

5. What are the best chemical options for yellow stem borer control?

 Use insecticides like Chlorantraniliprole or Cartap Hydrochloride as a last resort, following recommended dosages.

6. How can I prevent yellow stem borer infestations?

Maintain clean fields, rotate crops, and use resistant paddy varieties to minimize risks.

7. Are hybrid paddy varieties resistant to yellow stem borer?

Some hybrids show tolerance, but no variety is completely resistant. Choose varieties suited for your region.

 

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