IDETIFICATION AND CONTROL MEASURES OF RICE LEAFROLLER: (Cnaphalocrocis medinalis)
INODUCTION:
Rice leafroller, also known by leaffolder belongs to the order Lepidoptera (Lepidos=scales, Pteron =wings ). It occurs in all rice environments and are more abundant during the rainy seasons. They are commonly found in shady areas and areas where rice is heavily fertilized.
As the quantitiy of chemical fertilizer application increasing in the field, the infested population area of rice leafroller also increasing year by year. During the season of kharif crop in the country its very much important to know about the rice leafroller for the effective judicious control measure.
IDENTIFICATION OF INSECT:
Rice leafroller can be identified by the following characters:
It is a monophagous insect complete their life cycle by four stages.
Egg: Flat, oval in shape and yellowish white in colour.
Fig: Larva
Larva(caterpillar ): it is a damaging stage of insect, during this stage the leaves of the plant are observed folded, rolled and continuously webbed together with white patches on them indicating the spaces fed by caterpillar. When such folded leaves are unfolded larvae can also be seen.
Pupa: pupal duration is 7 to 10 days inside the folded leaves.
Adult: Moth is yellow brownish wings with many dark wavy strains in centre and dark band on margin of wings
Fig: Pupa Fig: Adult
Disc –shaped ovoid eggs laid singly.
Young larvae feeding on the base of the youngest unopened leaves.
IDENTIFICATION OF INFESTED PLANT:
Most of the insects in the crop field have the same way of feeding habits specially biting and chewing type insect. Rice leafroller infested plant should be identified by following ways:
- Caterpillar fold a rice leaf around themselves with silk strands.
- Longitudinal whitish and transparent streaks appear on the blade. Fig: Infested rice
- Presence of disc- shaped oval eggs or of fecal matter are also sings of infection.
- Leaf tips sometimes fastened to the basal part of leaves.
- Heavily infested fields appear scorched with many folded leaves.
CONTROL MEASURES:
Judicious management of insect and pest should be the most important point now a days because of many reason so by the following of Integrated Pest Management(IPM) system rice leafroller can be controlled by following ways:
Preventive Measures:
- Use resistant variety of rice to prevent outbreak.
- Alternate cropping pattern or fallow period system should adopt.
- Remove grassy weeds from fields and borders.
- Minimize the use of fertilizer.
- Avoid ratooning to long as this favors the disease.F
- Floodand plow fields after harvest to remove crop residues.
Biological control.
Make use of light traps to attract and collect adults. Also the protection and release of natural enemies, like predatory beetles, frogs and dragon flies or entomopathogenic fungi and viruses provides helpful. Spread of neem leaves randomly in the field deters adults from laying egg
Chemical control.
Always consider an integrated approach with preventive measures together with biological treatments if available. If infestation are high (>50%) during tillering, insecticide sprays based on the active ingredients:
- Chlorpyrifos 20 % EC at 2 lm/lit.
- Indoxacarb 15.8 EC at 0.7 ml/lit.
- Azadirachtin 10000 ppm at 2 ml/lit of water. Add sticking agent at 1 ml per litre of water.
- Cartap hydrochloride 50 % SP at 2 gm/lit.
- Profenofos 50 EC at 1.5 ml/lit.
About Writer: MANTU RAM CHAUDHARY (B.Sc.Agriculture,DIBNS,Dehradun)
Reference:
International Rice Research Institute( IRRI), Philippines.A text book of Entomology.A
TmilNaduAgriculture University, Ramanathauram.
Dolphin PG Institute of Bio-Medical and Natural Sciences, Dehradun
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