Efficacy of pre-emergence herbicides used in weed control of corn

Maize is a very susceptible crop to early competition of weeds. The use of post sowing and pre-emergence herbicides is a mandatory to reduce the impact of weeds on the crop. Two trials were conducted, under irrigation regime, during the growing season 2013-14 in Loukkos on a sandy soil and in Gharb on a clay soil. Weed flora recorded in trials sites was composed of 19 species belonging to 14 botanical families. Based on % cover of each species, Cyperus rotundus, Polygonum convolvulus and Urtica urens were dominant in Loukkos, however, Beta macrocarpa, Chrozophora tinctoria and Amaranthus blitoïdes were dominant in Gharb. All tested herbicides were selective of maize and Integrity, Lumax, Guardian, Prowl and Primextra efficacies on weed species were excellent. However, Dual Gold gave good efficacy on broadleaved species. As grasses,Paspalum distichum was tolerant to all herbicides, Digitaria sanguinalis was well controlled by all tested herbicides. Prowl and Dual Gold failed to control Phalaris brachystachys. The species susceptibility to herbicides varies with the herbicide.  Thus, the number of species not controlled (on 19) varies from 1 to 4. The maximum failure was observed with Dual Gold and the minimum with Lumax, Guardian and Primextra.

 Key words: Maize, herbicides, pre-emergence, efficacy, selectivity.