Six species of stemborer attack rice. These are the, , , , , and the .
Among the stem borers, the pink stem borer is less important. It is polyphagous and prefers sugarcane to rice.
What it does
Stem borers can destroy rice at any stage of the plant from seedling to maturity.
They feed upon tillers and causes deadhearts or drying of the central tiller, during vegetative stage; and causes whiteheads at reproductive stage.
Why and where it occurs
The stem borer larvae bore at the base of the plants during the vegetative stage. On older plants, they bore through the upper nodes and feed toward the base.
The yellow stem borer is a pest of deepwater rice. It is found in aquatic environments where there is continuous flooding. Second instar larvae enclose themselves in body leaf wrappings to make tubes and detach themselves from the leaf and falls onto the water surface. They attach themselves to the tiller and bore into the stem.
Striped stem borer is most abundant in temperate countries and in non-flooded areas. Their final instars remain dormant in temperate areas during winter.
The pink stem borer is found in upland rice, which is grown near sugarcane or related grasses. The presence of alternate hosts encourages the pink stem borer to develop, multiply and survive during winter or dry season. Unlike other species of stem borers, the pink stem borer lay bare eggs between the leaf sheath and the stem.
High nitrogenous field favors population buildup of the stem borers. Fields planted later favors more damage by the insect pests that have built up in fields that have been planted earlier. Stubble that remains in the field can harbor stem borer larvae and or pupae.
How to identify
Check the field for the following damage symptoms:
Deadhearts and whiteheads symptoms may sometimes be confused with damages caused by rats, neck blast, and black bug diseases.
To confirm stem borer damage, visually inspect rice crop for deadhearts in the vegetative stages and whiteheads in reproductive stages. Stems can be pulled and dissected for larvae and pupae for confirmation of stem borer damage.
Why is it important
Excessive boring through the sheath can destroy the crop. Its damage can reduce the number of reproductive tillers. At late infection, plants develop whiteheads.
How to manage
Content experts: JLA Catindig and KL Heong