Leaf-eating caterpillar and leaf webber: collect and destroy affected parts with caterpillars, and set a light trap (1/ha) to catch adults. Amaranthus weevil: destroy wild amaranthus nearby and affected plant parts with grubs and adults. The source advises avoiding sulphur sprays on amaranthus; a chemical leaf-spot spray is also listed — ask your officer.
Pending expert review
Source
Crop Production Guide – Horticulture Crops 2020 (Directorate of Horticulture and Plantation Crops, Tamil Nadu & Tamil Nadu Agricultural University (TNAU)), Amaranthus – Plant protection (pests), p. 156
