Maize Stem Borer Control

Symptoms

Young larvae feed in the central whorl producing rows of small shot holes across the leaves when they unfold. Older larvae bore into the stem, weakening it so it may break or lodge, and the central shoot can dry up to form a dead heart in young plants. Bore holes with sawdust like excreta are seen on the stem, and larvae may also tunnel into the cob shank.

Damage

The maize stem borer is one of the most important regular pests of maize in India and can cause yield losses commonly of 25 to 40 percent through dead hearts, broken stems, lodging and damage to the cob. Damage is worst when young plants are attacked at the whorl stage.

Organic & cultural control

Plough deep after harvest and destroy stubble and crop residue where larvae overwinter. Sow on time and avoid staggered sowing. Release the egg parasitoid Trichogramma at the recommended rate during the early crop stage and conserve natural enemies. Apply a small amount of dry sand mixed into the whorl or use neem based sprays on early larvae before they bore into the stem.

Chemical control

If borer attack crosses the threshold in the whorl stage, apply a registered insecticide such as chlorantraniliprole 18.5 SC as a spray directed into the whorl, or place recommended granules like cartap hydrochloride into the whorl so they act on larvae inside. Always follow the product label dose, observe the pre harvest interval and consult your KVK or agronomist before applying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Use deep summer ploughing and destroy residue to break the carryover of larvae. Sow on time and uniformly, follow crop rotation with non cereal crops, and intercrop with legumes to support natural enemies. Monitor the whorl from two weeks after emergence and use timely Trichogramma releases as a routine preventive step in borer prone areas.