Evaluation of broadleaf weeds control with some post-emergence herbicides in maize (Zea mays L.) in Iran

Registered dose of herbicides may be higher than rate required for controlling

weed species depending on growth stages. In order to study the effect of individual

post-emergence application of 2,4-D plus MCPA and three sulfonylurea herbicides at

four- to six-true leaf stage of weeds, experiments were conducted in 2011 at the

greenhouse of Agricultural Faculty of Ferdowsi University of Mashhad, Iran.

Treatments included untreated control and several rates of 2,4-D plus MCPA,

foramsulfuron, nicosulfuron and nicosulfuron + rimsulfuron on redroot pigweed,

common lambsquarters, common purslane and black nightshade. These herbicides

were more effective to control redroot pigweed than other weeds (except

nicosulfuron + rimsulfuron), thereupon minimum dose required for a satisfactory

efficacy of 90% reduction of redroot pigweed aboveground dry matter (ED90)

were 375.26, 23.51 and 63.81 g a.i h-1 of 2,4-D plus MCPA, foramsulfuron and

nicosulfuron, respectively. Nicosulfuron and nicosulfuron + rimsulfuron did not

control common lambsquarters effectively. Foramsulfuron had the lowest effect on

black nightshade and common purslane, so that minimum dose required for a 90%

reduction of black nightshade and common purslane aboveground dry matter were

52.42 and 60.26 g a.i h-1, respectively. Thus, these results showed that tank mixtures

with other herbicides effective in controlling broadleaf weeds may be required for

satisfactory weed control and reduction in sulfonylurea herbicides doses.

Keywords: Broadleaf weeds; Dose-response curve; Effective dose; Growth stage;

Sulfonylurea herbicides.