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Yellow stem borer (Scirpophaga incertulas) in paddy

Scirpophaga incertulas (Walker), the yellow stem borer, is a lepidopteran moth of the family Crambidae and the dominant stem borer of cultivated rice in South and Southeast Asia. Its larvae tunnel inside rice tillers and damage all crop stages.

Identification and symptoms

Diagnostic damage is the dead-heart symptom on vegetative tillers - the central whorl wilts and pulls out easily - and the white-ear symptom on reproductive tillers, where the panicle is killed at the boot stage and stands erect and bleached above the canopy. Adults are small ochreous-buff moths bearing a single dark spot on each forewing. Eggs are laid in masses on leaf tips, covered with buff scales.

Host crops and life cycle

The pest is essentially monophagous on cultivated rice and breeds in multiple overlapping generations through a cropping season. Carry-over between crops occurs on stubble and ratoons. The species co-occurs with rice leaf folder (Leaf Folder Paddy, Leaf Folder Paddy 2) and is widely co-managed using overlapping chemistries.

Damage and economic impact

Yield loss scales with infestation: approximately 2.5% yield loss for every 1% of dead-hearts and 4% for every 1% of white-ears in published thresholds. Susceptible long-duration fine-grain varieties suffer particularly heavy white-ear damage if boot-stage borer control is inadequate.

Management

  • Cultural: avoid late and staggered planting, clip leaf tips before transplanting to remove egg masses, collect and destroy egg masses through nursery rouging.
  • Biological: conserve and release Trichogramma japonicum egg parasitoids.
  • Chemical: ICAR research documents chlorantraniliprole 18.5 SC sprays and chlorantraniliprole 0.4% GR broadcast at tillering as superior to cartap hydrochloride in reducing both dead-heart and white-ear damage, with no phytotoxicity and below-quantification grain residues. Treatments integrate with the tillering spray (Paddy Tillering Spray 25 50 Dat) and boot-stage management (Paddy Panicle Stage Management) windows.

See also: Stem Borer Paddy, Leaf Folder Paddy, Leaf Folder Paddy 2, Brown Planthopper Paddy, Gall Midge Paddy, Paddy Tillering Spray 25 50 Dat, Paddy Panicle Stage Management.

References

  1. Rice Yellow stem borer. ICAR-CRIDA NAIP.
  2. Bio-efficacy of chlorantraniliprole 0.4% GR in rice. ICAR Indian Journal of Agricultural Sciences.