What's eating my konjac?

Konjac corms and foliage are targeted by aphids, caterpillars, and soil-dwelling pests such as vine weevil grubs. Slugs and snails shred the large leaves in humid gardens. The corms can rot if wireworms or other root feeders are active in the soil. Aphids are the most frequent above-ground nuisance.

Clustered colonies on petioles and undersides of the single compound leaf; sticky honeydew and distorted new growth. Knock off with a strong water jet; apply insecticidal soap or neem oil spray weekly until clear.

Large ragged holes or complete stripping of the leaf blade, worst after rain in spring and autumn. Apply iron phosphate slug pellets around the stem; use copper tape on containers; hand-pick at night.

Clean-cut notches or holes in the leaf; frass visible on foliage or soil surface. Hand-pick caterpillars; use Bacillus thuringiensis (Bt) spray on affected foliage for heavier infestations.

Corm surface gnawed; plant wilts suddenly even with adequate water as roots and corm tissue are consumed underground. Apply nematodes (Steinernema kraussei) to moist soil in late summer; inspect and destroy grubs when lifting corms.