WEEDS CONTROL IN INDUSTRIAL HEMP (Cannabis sativa L.) BY USING HERBICIDES IN PRE-EMERGENCY AND POST-EMERGENCY

The impressive production potential of industrial hemp (Cannabis sativa L.) is limited by the lack of herbicides authorized for use in this crop in Romania. The aim of this research was to establish the tolerance of industrial hemp to herbicides applied in preemergence and postemergence to control dicotyledonous weeds: Amaranthus retroflexus L., Atriplex patula L., Chenopodium album L., Polygonum convolvulus L., Sinapis arvensis L., Xanthium strumarium L., respectively monocotyledonous: Echinochloa crus-galli L., Setaria spp., Sorghum halepense (L.) Pers. and Poa annua L. A number of 13 herbicides were tested, and the results demonstrate that monocotyledonous weeds can be controlled very well by the active substances cletodim (89.67%) and fluazifop-P-butyl (91.33%), and dicotyledonous weeds are effectively combated by aclonifen (80.0%) applied in pre-emergence and oxyfluorfen (84.0%) applied pre-emergence, but oxyfluorfen causes phytotoxicity (9.0%) of the treated hemp plants. Also, the good effect of clopiralid on Xanthium strumarium and other weeds from the Asteraceae family should be mentioned.