Influence of infestation with Echinochloa crus-galli species on crop production in corn.

The problem of the influence of different species of weeds on the production of agricultural plants has been studied by many researchers. The damage caused by weeds in maize crop is mostly of 30-70%, and when the infestation is strong the culture can be fully compromised. Our research highlight takes place in Transylvania, and focuses on the influence of Echinochloa crus-galli species (L.) Pal. Beauv. and other weeds on corn production, according to the degree of infestation. The research was conducted at the University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca, Romania. The research was done on two agrofunds: unfertilized and mineral fertilized with NPK 100 kg s.a./ha. The unfertilized maize crop has been made in four variants with different degrees of infestation of Echinochloa crus-galli, from about 40 to 100 plants/m 2 . Four herbicides (isoxaflutol 750 g/l; acetoclor 860 g/l; dimetenamid 900 g/l; bentazon 320 g/l + dicamba 90 g/l) were used for weed control in fertilized plots . Weed biomass and corn plant and grain production were measured in the ripening stage. Corn invaded by weeds grew weakly and had a yellowish green color; in unfertilized corn plots a stratified weed population developed: Echinochloa crus-galli dominated in the upper layer, Setaria glauca (L.) Beauv. developed in the middle and a number of dicotyledonous species in the lower layer. In fertilized variant, the competition between weeds and maize on one hand and between monocotyledonous and dicotyledonous species on the other hand was more balanced, the biomass of dicotyledonous species ranged from 1700 kg/ha in unfertilized plots to 4100 kg/ha in mineral fertilized plots. The amount of weeds, obviously influenced production levels of maize grain and green mass. Production losses in terms of green mass per hectare can be considered equal to the weight of green weeds. At a density of 104 plants/m 2 of Echinochloa crus-galli with green mass of 18,052 kg/ha corn crop was fully compromised.