Damage

The larvae that have penetrated a tiller feed on the inner surface of the stem walls and thus interrupt the movement of water and nutrients. Tunneling by the larvae weakens the rice stem, which then break easily. Damage depends on the age of the plant when it is attacked.

If damage occurs when the plant are young, the central leaves of the damaged is called deadhearts. If the damage occurs after the spikelets form panicles turn white and no grain filling occurs. The damage panicles are called whiteheads. Tiller damage from diseases such as kresek assembles deadhearts. Drought can also cause whiteheads.

Panicles damage by stem borers can easily be pulled cut buy hand and may show inseck feeding near the base. Stem borer damage tillers are filled with frass (waste from the digestive tract) and have larval entrance and exit holes.

Management

Cultural control

v Plant an early-maturing rice variety. The stem borer completes fewer generations in an early-maturing variety. Populations on such a variety are lower and damage is reduced.

v Plant fields in an area within 3 to 4 weeks, which is less than the time for one stem borer generation. Stem borer complete fewer generations when fields are planted synchronously.

v Field planted later may be severely damage by stem borers that have built up in the fields planted earlier. Stem borers in late planted crops may be carried over to attack a second rice crop. Stem borers on the first crop will not be carried over to the second rice crop if the stubble is plowed under after the first crop is harvest, and the ground is left fallow for at least 3 to 4 weeks between crops.

v Remove rice stubble and straw. Plow stubble immediately after harvest to destroy yellow and white stem borer larvae and pupae.

v Cut stubble close to the ground so that many of the remaining striped, dark-headed, and pink stem borer larvae are removed with the straw. Burn or sun-dry straw after threshing to destroy stem borer larvae.

v Avoid excessive nitrogen fertilizer by splitting fertilizer application.

v Remove seedlings with stem borer egg masses before transplanting

v Flooding a field will not control all stem borers. The yellow stem borer is in fact a major pest of deepwater rice and the larvae can complete their development.

Resistant varieties.

v Many improved varieties have moderate resistance to stem borers. Because some chemicals in the rice plant effect the moth, the plant become less attractive for egg laying and larvae that emerge have a lower rate of survival, are small, and take a longer time to mature.

v High tillering varieties can compensate more for deadhearts during the tillering stage than low tillering varieties can.