Cotton is highly susceptible to the interference imposed by weed community,
being therefore essential to adopt control measures ensuring the crop yield. Herbicides are
the primary method of weed control in large-scale areas of production, and usually more
than one herbicide application is necessary due to the extensive crop cycle. This study
aimed to evaluate the selectivity of different chemical weed control systems for conventional
cotton. The experiment took place in the field in a randomized block design, with twenty nine
treatments and four replications in a split plot layout (adjacent double check). Results showed
that triple mixtures in pre-emergence increased the chance of observing reductions in the
cotton yield. To avoid reductions in crop yield, users should proceed to a maximum mixture
of two herbicides in pre-emergence, followed by S-metolachlor over the top, followed by one
post-emergence mixture application of pyrithiobac-sodium + trifloxysulfuron-sodium.