DISEASE, PEST & ITS MANAGEMENT IN RICE

INTRODUCTION:

Scientific name: Oryza sativa
Family: Gramineae

Rice is the stable food of more than 60%of the world population. In Asia, major rice producing countries are India ,China ,Japan and Pakistan.Paddy is the grain enclosed with seed coat called hull. Rice [chamal] is the grain devoid of hull.

IMPORTANCE OF RICE

1-Economic value
2-Animal nutritional value
3-Industrial value
4-Socio cultural and religious value
5-Other values:
-Straw used for mushroom production.
-Straw used as housing material
-Hull use as bedding material for poultry.

DISEASES OF RICE

Various diseases occurs in rice which causes loss or reduction in yield and quality of crops.

The major diseases of rice are:

1-Blast or necks rot
2-Brown spot
3-Sheath blight of rice
4-Foot rot

1.BLAST OR NECK ROT:
It is caused by fungus Pyricularia oryzae.This disease is responsible for approximately 30%of rice production losses .

SYMPTOMS:

Initial symptoms appear as white to grey green lesion or spots with dark green boarder.
Old lesions on the leaves are elliptical or spindle and whitish to gray center’s with red to brownish or necrotic border.

CONTROL MEASURES:

-Use disease resistance varieties like Chaita-2,Radha-12,Khumal-11
-Avoid excessive nitrogen application rates.
-Fungicides like triazoles can be used to control the blast.

2.BROWN SPOT:
Caused by fungus Bipoloris oryzae

SYMPTOMS:

Brown is the indicator of unfavorable growing condition including insufficient nitrogen inability of plant to use nitrogen because of root rot or other unfavorable condition.
It is a fungal disease in which brown spots appear on the leaf.

CONTROL MEASURES:

-Use disease resistance varieties.
-Crop rotation
-Proper land leveling
-Proper fertilization
– Seed protectant fungicides reduce the severity.

3.SHEATH BLIGHT OF RICE:
Decrease yield up to 50% and reduce quality.

SYMPTOMS:
-On the leaf sheath oval or elliptical or irregular greenish grey spot are formed.
-The infection extends to the inner sheath resulting in death of plant.

CONTROL MEASURES:

1-Seed treatment with carbondizam.
2-Provide wider spacing.
3-Drain rice field relatively early in cropping season to reduce sheath blight epidemics.

NUTRIENT DEFICIENCY:

This disease is caused by the deficiency of zinc.

-It is non-parasitic and non-infectious disease.
-Yield losses up to 25%.
-At first leaf become yellow color and then brown spots are formed.
-Chlorosis is seen in affected leaves.
-Plant cannot attain good height.

CONTROL MEASURE:

-Khaira disease can be control by spraying of Znso4 in nursery bed of rice before transplanting in main field.
-Use fertilizer that generate acidity.
-Water logging should be avoided and there should be proper management of drainage in field.

INSECTS :

-Rice bug
-Brown plant hopper
-Rice borer
-Army worms

1.RICE BUG:

Scientific name: Leptocorisa oratorius
-Rice bugs damage rice by sucking out the content of developing grain from pre-flowering spikelet’s to soft dough stage.
-Discoloration
-Adult are active during the late afternoon and early moarning.

MANAGEMENT:
-Remove weed from field and surrounding area .
-Capturing rice bug in early moarning or late afternoon.
-Use cypermetherin.
-Encourage biological control agent some wasp and grasshopper and spider attack rice bug or rice bug egg.

2.BROWN PLANT HOPPER :

-Occurrence of disease is high in jestha ,ashar.
-Growth of plant decrease.
-Plant becomes yellowish.

MANAGEMENT:
-Management of weed.
-Use light trap to control their population.
-Use those variety resistance to fight against brown plant hopper.

3.BORER

SYMPTOMS:
-Dead tiller can easily pulled from the base during vegetative stage.
-Tiny holes are seen on the steams.

MANAGEMENT OF BORER:
-Use resistance variety .
-At seed bed and transplanting hand picking and destroy of egg mass.
-Before transplanting cut the leaf top to reduce carry over of egg from seed bed to the field.

4.ARMY WORM

-It occur in group and mostly active at night time.
-They hide in the soil or at bunds.

MANAGEMENT:

-Deep ploughing should be done
-Drain the water in field.
-Allow ducks in the field.
-Flooding the nursery makes the hiding larvae come to the surface and thus they are picked by birds.

Writer: PRATIKASHYA POKHREL (Student, Bsc. Ag IAAS Paklihawa Campus)