Most producers apply little or no fertilizer to amaranth or they manage it as they would wheat. Nitrogen promotes vegetative growth which can result in lodging especially under irrigation. Manure is used to stay within the guidelines of organic production. Virus symptoms have been observed in the Panhandle, but not identified at this point. Several insect species damage amaranth including the flea beetle, amaranth weevil, tarnished plant bug, and lygus species.
Flea beetles attack young, succulent plants and can cause serious damage.
The tarnished plant bug damages the crop by feeding on the immature grain, resulting in discolored, shriveled seed. Amaranth weevil larvae bore into the root and stem. Weakened plants then allow entrance of disease organisms, resulting in lodged plants. No insecticides are labeled. For many producers, weed control is their biggest problem.