Cytochrome P450 enzymes inhibitor in the control of Digitaria insularis

ABSTRACT Herbicide interactions can be synergic, additive, or antagonist when mixed in the spray tank. A good example is an association between 2,4-D and graminicides. One hypothesis is that 2,4-D contributes to increasing the Cytochrome P450 activity, which may be one of the causes of antagonism. This study aimed to investigate the use of CYP450 enzymes inhibitor associated with the herbicide mixtures 2,4-D and ACCase inhibitors in vivo on the control of Digitaria insularis. The experiment was performed using a randomized block design in a factorial scheme of 6x2 with four replications. Factor A consisted of untreated check, 2,4-D (1005 g a.e ha-1), clethodim (192 g a.i ha-1) and haloxyfop (62.4 g a.i ha-1), 2,4-D + clethodim (1005 g a.e ha-1+192 g a.i ha-1), and 2,4-D + haloxyfop (1005 g a.e ha-1 +62.4 g a.i ha-1). Factor B represented the presence or absence of malathion (1000 g ha-1) applied two hours before applying the herbicides. A physicochemical test was performed to verify the compatibility of the herbicides in the tank. Malathion application performed two hours before applying the herbicide mixtures (2,4-D and clethodim/haloxyfop) did not provide adequate control of sourgrass, suggesting that CYP450 enzymes inhibited by malathion are not involved in the antagonistic effect between 2,4-D and both graminicides in the management of sourgrass. The 2,4-D + haloxyfop in tank mix demonstrated less efficacy in controlling sourgrass than 2,4-D + clethodim, but both mixtures were incompatible in the tank mix, which may be associated with reduced efficacy in sourgrass management. RESUMO As interações entre herbicidas quando misturados na calda de pulverização podem ser sinérgicas, aditivas ou antagônicas. Um exemplo de antagonismo está na associação entre os herbicidas 2,4-D e graminicidas. Há a suspeita de que o 2,4-D contribui para o aumento da atividade do Citocromo P450, podendo ser esta uma das causas do antagonismo. O objetivo deste estudo foi investigar o uso do inibidor das enzimas CYP450 in vivo, associado às misturas de herbicidas 2,4-D e inibidores da ACCase, no controle de Digitaria insularis. O experimento foi realizado em delineamento de blocos casualizados em esquema fatorial 6x2 com quatro repetições, sendo o fator A os herbicidas: controle 2,4-D (1005 g a.e. ha-1); cletodim (192 g a.i ha-1) e haloxifope (62,4 g a.i ha-1), 2,4-D+cletodim (1005 g a.e ha-1+192 g a.i ha-1), 2,4-D+haloxifope (1005 g a.e ha-1 +62.4 g a.i ha-1); e o fator B a pre