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Yellow stem borer in paddy (mogi purugu)

The yellow stem borer, Scirpophaga incertulas (Walker), known in Telugu as mogi purugu, is the most damaging stem borer of tropical and lowland rice in South and Southeast Asia. Larvae tunnel inside tillers, killing growing points and developing panicles.

Identification and symptoms

Two characteristic symptom phases occur depending on crop stage. During vegetative growth, larvae destroy the growing point inside a tiller, producing a 'dead-heart' - the central whorl pulls out easily and dies. During booting and heading, larvae destroy the developing panicle inside the boot, producing 'white-eared' empty panicles that stand erect and bleach white against the canopy. Adults are small yellow-buff moths with a single dark spot on each forewing.

Host crops and life cycle

The pest is monophagous on rice with multiple overlapping generations through a cropping season. Eggs are laid in masses on leaf tips, covered with buff-coloured scales. Carry-over between crops is on stubble and ratoons.

Damage and economic impact

Published damage thresholds note approximately 2.5% yield loss for every 1% of dead-hearts and 4% yield loss for every 1% of white-ears. Susceptible long-duration fine-grain varieties such as Rnr 15048 can experience heavy white-ear damage if boot-stage borer management is inadequate.

Management

  • Cultural: avoid late and staggered transplanting; collect and destroy egg masses in nursery and early field; clip leaf tips before transplanting to remove egg masses.
  • Biological: conserve Trichogramma japonicum egg parasitoids; release commercial Trichogramma cards.
  • Chemical: ICAR field studies show chlorantraniliprole 18.5 SC sprays and chlorantraniliprole 0.4% GR broadcast at tillering (Paddy Tillering Spray 25 50 Dat) outperform cartap hydrochloride, with no phytotoxicity and below-quantification grain residues. Cartap, fipronil and fenitrothion are alternative actives. Boot-stage management (Paddy Panicle Stage Management) is critical for white-ear control.

See also: Yellow Stem Borer Paddy, Leaf Folder Paddy, Brown Planthopper Paddy, Gall Midge Paddy, Rnr 15048, 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 J Agric Sci.
  3. Rice Stem Borer: Scirpophaga incertulas. CABI Plantwise.