What's eating my eleocharis dulcis?

Eleocharis dulcis (Chinese water chestnut) is an edible aquatic sedge grown in shallow water. The main pests are sedge-feeding caterpillars and rust flies in warmer climates, slugs at the water margin, and wading birds that probe the mud for corms. Good water depth management and row covers reduce most damage during establishment.

Larvae skeletonise or shred green stems, reducing photosynthesis and corm yield. Hand-pick egg masses and caterpillars; apply Bacillus thuringiensis (Bt) spray to foliage as a low-risk bio-control.

Rasp young shoots at the waterline, especially during establishment in spring. Set slug traps (beer or inverted grapefruit) at the pond margin; apply iron-phosphate pellets away from water.

Probe and scratch the mud to unearth corms; also flatten stems. Cover growing beds with wire mesh or netting; a motion-activated sprinkler deters herons effectively.