KERALA AGRICULTURAL UNIVERSITY
 
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Table 9. Economic threshold levels (ETLs)

Crop stage and pest Economic threshold levels

A. Nursery
1. Green leaf hopper 1-2 insects/m2
2. Gall midge 1 silver shoot (gall)/m2
3. Stem borer 1 moth or 1 egg mass/m2
4. Blast 5% disease severity

B. Planting to pre-tillering
1. Leaf folder 2 freshly damaged leaves/hill
2. Yellow stem borer 5% dead hearts or one egg mass or one moth/m2
3. Gall midge 1 gall/m2 in endemic areas or 5% affected tillers in non-endemic areas.
4. Brown plant hopper 5 to 10 insects/hill
5. Green leaf hopper 10 insects/hill (in RTV endemic areas 21 insects/hill)
6. White backed plant hopper 10 insects/hill
7. Rice Hispa 2 adults or 2 damaged leaves/hill

C. Mid-tillering
1. Leaf folder 2 freshly damaged leaves/hill
2. Stem borer 10% dead heart or 1 moth or 1 egg mass/m2
3. Gall midge 5% silver shoots
4. Brown plant hopper 10 insect/hill
5. Green leaf hopper 10-20 insects/hill
6. Hispa 2 adults or 2 damaged leaves/hill
7. Blast Light (5-10% disease severity)
8. Bacterial blight Light (2 to 5% disease severity)
9. Sheath blight 10% or more affected tillers
10. Tungro 1 affected hill/m2

D. Panicle initiation to booting
1. Stem borer 1 egg mass or 1 moth/m2
2. Leaf folder 2 freshly damaged leaves/hill
3. Green leaf hopper 20 insects/hill
4. Brown plant hopper 15 to 20 insects/hill
5. White backed plant hopper 15 to 20 insects/hill
6. Blast 5 to 10% leaf area damaged
7. Bacterial blight Light to moderate (2-5% disease severity)
8. Sheath blight 10% or more tillers affected

E. Flowering and after
1. Brown plant hopper 25 to 30 insects/hill
2. Climbing cutworm 4-5 larvae/m2
3. Rice bug 1 or 2 bugs/hill
4. Blast 5% leaf area damaged or 1 to 2% neck infection
5. Sheath rot / brown spot / slight panicle discolouration 2-5% tillers affected
6. Sheath blight 10% or more tillers affected

Source: Manual on Integrated Pest Management in Rice, Directorate of Plant Protection, Quarantine and Storage.

Note:

(1) The population should be estimated on the basis of careful and regular surveillance.

(2) When natural enemies of brown plant hopper, green leaf hopper, stem borers and leaf folders are present, application of chemical measures can be delayed or dispensed with.


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Citation:
Kerala Agricultural University. 2002. Package of Practices Recommendations: Crops. 12th Edition
(eds. A. I. Jose et al.). Kerala Agricultural University, Trichur. 278p.