Yellow Stem Borer in Rice and Its Management

Yellow Stem Borer in Rice and Its Management

The yellow stem borer or rice yellow stem borer,(Scirpophaga incertulas) is a species of moth of the family Crambidae.Stem borers can destroy rice at any stage of the plant from seedling to maturity. It is polyphagous and prefers sugarcane to rice.Stem borer have many species among them six species attack the rice. It was described by Francis Walker in 1863. It is found in Afghanistan, Nepal, north-eastern India, Sri Lanka.Yellow stemborer damage can lead to about 20% yield loss in early planted rice crops, and 80% in late-planted crops.It causes dead heart or drying of the central tiller during the vegetative stageand whiteheads, where the emerging panicles are whitish and unfilled or empty in reproductive stage. They occur in all rice growing areas, and can locally reach relatively high densities in some years.

Identification

Egg :

Eggs are creamy white, flattened, oval and laid in a mass which is covered with buff coloured hairs. They are laid mostly near the tip of the leaves. Egg period is 5-8 days.

Larva :

Pale yellow with dark brown head having prothoracic shield. Larval period is 28 to 30 days.

Pupa :

White silken cocoon. Pupation takes place inside the rice stem, straw or stubble. Pupal period is 8 to 10 days.

Adult :

Female moth :

Has bright yellowish brown with a black spot at the centre of the fore wings and a tuft of yellow hairs at the anal region.

Male moth :

Smaller with pale yellow forewings without black spot.

Symptom of Damage :

Presence of brown coloured egg mass near the leaf tip.In vegetative stage larva enters the stem and feeds on the growing shoot and causes drying of the central shoot known as “dead heart”.In grown up plant whole ear heads become dried and yield chaffy grains called as “white ear”.

Nature of Damage :

In the vegetative phase, the central shoot dies off turning yellow in colour (dead heart). In the ear bearing stage, the ear head appears completely chaffy and white in colour (white ear head). Both come out easily when pulled up and show indication of feeding injuries at the base.

Management Strategies :

Cultural Methods:

• Field should be necessarily be scouted during the vulnerable crop growth stages for early detection of dead hearts and white ear.

• Removal and proper disposal of stubbles will keep the borer population low in next crop.

• Grow resistant varieties

• Apply the fertilizers in split applications during the season.

• Raise level of irrigation water periodically to kill the eggs.

• Apply nitrogenous fertilizers and manure moderately.

• Clip the tip of the seedlings before transplanting to eliminate egg masses.

• Collect and destroy the egg masses.

• Avoid close planting and continuous water stagnation at early stages.

• Pull out and destroy the affected tillers.

• Harvest the crop up to the ground level and disturb the stubbles with plough immediately after the harvest to keep the borer population low in next crop.

Chemical Methods:

• ETL : 2 egg masses/m2 (or) 10% dead heart at vegetative stage (or) 2% White ear at Flowering stage.

• When natural enemies of stem borers are present, application of chemical measures can be delayed or dispensed with.

• The newly hatched borer larvae must be flit with 2 rounds of quinalphos or phosphomidon at 1000ml/ha at 7 days interval.

• Spray any one of the following based on ETLs :Monocrotophos 36 SL 1000 ml/ha (or) Quinalphos 25 EC 1000 ml/ha (or) Phosphamidon 40 SL 600 ml/ha (or) Profenophos 50 EC 1000 ml/ha.

• Applications of Chlorantraniliprole at 40 g.a.i./ha was found to be efficacious against S. incertulas.

Biological Methods:

• Release of egg parasitoid Trichogramma japonicum thrice at weekly interval starting 28 days after transplanting @ 5 cc (1 lakh egg parasitoids)/ha/release. Followed by the release of Trichogramma japonicum at 35 and 42 DAT.

• Apply Bacillus thuringiensis var kurstaki at 2.5 kg/ha to reduce the oviposition by the stem borer.

• Release the egg cards in field during morning hours. Tie the egg cards under the leaf surface facing outside.

• Avoid spraying of chemicals on three days before and upto to seven days after field release of egg cards.

Natural enemies and predators:

Natural enemies :

Tetrastichus schoenobii – Wasp

Telomomous rowani – Wasp

Stenobracon nicevillei – Braconidae

Cotesia flavipes – Braconidae

Agriocnema pygmae – Damselfly

Predators :

Lycosa pseudoannulata – Spider predator