They eat the growing point of a maize plant which kills it. They also damage forming grains in the cob.
Start looking for signs of damage when plants are 2-4 weeks old & if you see holes in the emerging leaves, put a pyrethroid based insecticide in the funnel to control them.
Cutworms are greasy-looking, greyish caterpillars which cut the crop at the ground level and also feed on the leaves.
Apply pyrethroid sprays in bands over the rows.
MLND is caused by 2 viruses. On their own, these viruses are not bad. When your maize gets both viruses, it will get MLND and die. Signs of MLND include drying leaves, rapid yellowing of leaves, no tasselling, abnormal or no ears, rotting cobs.
There is no treatment to MLND. If you notice attack, uproot the affected plants and burn them away from the field. Do not grow maize in the same field for the next 2 seasons.