The Cupuassu tree Theobroma grandflorum is a typical Amazonian plant. Its fruit, the cupuassu, is one of the most popular fruits in the region with an increasing demand due to its organoleptic characteristics and multi use by the agro industry. Its cultivation, however, is still very rudimentar and its production is highly affected by weeds. The objective of this study is to evaluate the effects of the herbicides alachlor and haloxyfop on weed control and selectivity for the leguminous plants Mucuna cochinchinensis and Pueraria phaseoloides and young cupuassu trees. This experiment was conducted under field conditions to evaluate the effect of herbicides on shoot dry matter production and leaf area index (LAI) of the weeds and leguminous plants and their phytotoxicity to cupuassu trees. Regarding the weeds, alachlor applied at 4.00 kg ha-1 reduced dry matter production by 75.60% and LAI by 64.02 %, whereas haloxyfop inhibited 62.51% of the dry matter accumulation and 64.23% of LAI. The herbicides were selective to the leguminous plants and haloxyfop at 0.12 kg ha-1 stimulated dry matter production of the aerial part in 180.15% and LAI in 146.68 %. The herbicides did not cause any injury to the cupuassu tree or to the leguminous plants and provided over 60% of weed control.
weeds; native fruit tree; Theobroma grandiflorum; Amazonian region
