When not grown on purpose, these grasses may become a very large nuisance to farmers. In particular Common Barnyard Grass (E. crus-galli) is notorious in this regard; it is not easily suppressed by living mulch such as Velvet Bean (Mucuna pruriens vat. utilis). Early Barnyard Grass (E. oryzoides) is a well-known example of Vavilovian mimicry: the plants have evolved to resemble rice (Oryza), enabling them to escape weeding more easily .
Among the plant pathogens that affect this genus are the sac fungus Cochliobolus sativus – which has been noted on Common Barnyard Grass – and rice hoja blanca virus. Both affect many other grass species, in particular most important cereals, and Echinochloa weeds may serve as a reservoir. The fungi Drechslera monoceras and Exserohilum monoceras have been evaluated with some success as potential biocontrol agents of Common Barnyard Grass in rice fields; more research is necessary however because they too may not be host specific enough to be of practical use.
Read more about Echinochloa: Selected Species