The objective of this work was to evaluate the efficacy of imazapic+imazapyr in controling purple nutsedge and its effect on the population of denitrifying bacteria in soil cultivated with corn. The trial was set up in 0.70 x 0.30 x 0.30 m boxes where imidazolinone tolerant corn (C901CL) was seeded together with 50 purple nutsedge bulbs. The experimental design was randomized with six replications. The treatments were: 1) corn without nutsedge; 2) corn with nutsedge; 3) corn with cut nutsedge; 4) corn with nutsedge treated with imazapic+imazapyr (63+21 g ha-1 i.a) applied in post-emergence and 5) corn with nutsedge treated with imazapic+imazapyr (63+21 g ha-1 i.a), applied in pre-emergence. The herbicide was efficient when applied in post-emergence, reducing in 41% the setting of aerial parts of the nutsedge with visual control effect of 88%, twenty-one days after spraying. The soil denitrifying bacteria increased six and ten-fold, 24 and 54 days after corn seeding, respectively, in the presence of purple nutsedge. The application in post-emergence reduced the denitrifying population to 1.91x10(5) MPN (most probable number) , 89% less than the non-weeded check (16.78x10(5) MPN).
bacteria; pseudomonas; nitrogen; volatilization; competition
