PEST MANAGEMENT DECISION GUIDE: GREEN AND YELLOW LIST
Paddy armyworm on rice
Mythimna separata Fauzi kira
- Rotate rice with vegetables as rice and other cereal crops are major hosts of paddy armyworm.
- Control grassy weeds in the rice field as they are alternative hosts.
- Conserve natural enemies such as Cotesia or Trichogramma wasp, and Carabid ground beetles by reducing pesticide use and growing flowering plants along border.
- Apply recommended dose of nitrogen fertilizer (100 kg N /ha) as too vigorous growth can increase armyworm infestation
- Use 2-5 light traps/Ha at the edge of the field and examine traps weekly for moths.
- After observing first moths in light traps, start monitoring the rice plants weekly to check caterpillar damage in crop (massive leaf removal, often including leaf veins) as damage occurs suddenly.
- Stout, hairless and brown caterpillars with a narrow, white dorsal line. Caterpillar curls to form C shape if disturbed.
- During grain filling stage, the larger caterpillars cut off panicles at their base causing some to bend while others to fall to the ground.
- Apply control measures if 1-5 larvae/hill during pre-panicle stage and 1 larva/hill at panicle stage are observed.
- Hand-pick egg masses (laid in single or double rows between the base of the leaf sheath and stem, which are not covered with hair) or larvae from seedbeds or a young crop and destroy them.
- Flooding of the nursery bed/ main field and dragging ropes across the top of the rice plants to detach and drown the swarming larvae.
- Use insecticides to control the larval stage. Do not mix pesticides. Alternate insecticides to avoid pest resistance development.
- When using a pesticide or botanical, always wear protective clothing and follow the instructions on the product label.
- Always consult recent list of registered pesticides from Pesticide Registration and Management Division, Nepal (www.prmd.gov.np)
Spray Azadirachtin –products, IRAC Group UN, Multi site action.
Toxicity not classified by WHO, but unlikely to present acute hazard in normal use. Restricted re-entry interval (r.e.i.) 1 day after spray. Max 3-4 sprays per season at minimum 7 days interval.
Bacillus thuringiensis (take Lepidopteran larvae active strain), IRAC Group 11A, Secondary contact action but pests need to ingest it.
WHO toxicity class III (slightly hazardous). r.e.i. 1 day after spray. Max. 3-4 sprays per season at minimum 7 days interval. Selective pesticide, thus less harmful to non targets.
Spray Cypermethrin –products, IRAC Group 3A (Pyrethroids), broad- spectrum insecticide. Non-systemic with contact and stomach action on caterpillar
WHO class II (moderately acute hazardous). r.e.i. 1 d after spray. Max. 2 sprays per season at min 14 d interval. Do not spray during day time (toxic to bees). Do not spray near water sources (harmful to aquatic organisms).
Spray Chlorpyrifos –products IRAC Group 1B (Organophosphates)(250 ml/Ha), broad- spectrum, contact insecticide with knockdown effect.
WHO class II (moderately acute hazardous); r.e.i. 1 day after spray. Max. 2 sprays per season at min 14 d interval. Toxic to beneficial insects, bees, aquatic organisms.
CREATED/UPDATED: May 2017
PRODUCED BY: Plantwise
©CAB International. Published under a CC-BY-SA 4.0 licence.