Management of Eleusine indica and Digitaria insularis with Herbicides in Association with Cover Plants

Aims: This study aimed to evaluate the control of Eleusine indica Gaertn. and Digitaria insularis (L.) Fedde through the combination of soil cover with green manure straw and herbicides applied in pre-emergence.

Study Design: Each weed species was evaluated in different experiments. The experiments were set up in a greenhouse in a completely randomized design and arranged in a factorial scheme (5×4)+2, with four replications.

Place and Duration of Study: Center of Agricultural Sciences, São Paulo, Brazil, from May 2019 to May 2020.

Methodology: Seeds of Digitaria insularis and Eulesine indica were sown at a depth of 1 cm from the soil surface. Then, the pots were watered, and the straw of Cajanus cajan, Sorghum bicolor, Crotalaria juncea, Crotalaria spectabilis, and Crotalaria breviflora was deposited on the surface. The pre-emergence herbicides trifluralin (900 g ai ha−1), pendimethalin (1200 g ai ha−1), clomazone (1000 g ai ha−1), and s-metolachlor (1920 g ai ha−1) were applied one day after the weed seeds were sown. The percentage of weed control was evaluated at 10, 20, and 30 days after emergence (DAE). The plant shoot was cut at 30 DAE and the weight of dry biomass was determined. The control without herbicide and with soil cover crop and no herbicide and no soil cover were also evaluated.

Results: Sorghum bicolor, Cajanus cajan, and Crotalaria breviflora were the most effective in controlling Eleusine indica when no herbicide was applied. Only Sorghum bicolor showed a satisfactory control of Digitaria insularis without the use of chemical management (above 80%). The association of pre-emergence herbicides with soil cover showed high control of weeds.

Conclusion: The results showed that the association between chemical and cultural methods is an effective alternative to control Eulesine indica and Digitaria insularis.