Table 6.

Overall essential oils (EOs) efficacy per species and per treatment. Treatments were: T. capitata EO (T1, T2 and T3 are 4, 8 and 12 µL mL⁻¹ doses), M. piperita EO (M1, M2 and M3 are 12, 16 and 20 µL mL⁻¹ doses) and S. chamaecyparissus EO (S1, S2 and S3 are 12, 16 and 20 µL mL⁻¹ doses) applied by irrigation. Cw (only water, neithr Fitoil nor EO application), Cf (0.03 μL Fitoil g⁻¹ of soil, no EO application). The efficacy (E) of a given EO was considered as its capacity to kill the plants and was assessed by attributing the value 0 if the plant was alive and 100 if the plant was dead (it is dimensionless). Data are the arithmetic mean of 10 replicates.

Species	Efficacy
Amaranthus retroflexus	64 a
Portulaca oleracea	25 c
Avena fatua	52 a
Echinochloa crus-galli	38 b
Treatment/Dose	Efficacy
Cw	0 g
Cf	0 g
T1	30 ef
T2	70 bc
T3	97 a
M1	47 d
M2	70 bc
M3	82 ab
S1	13 fg
S2	40 de
S3	55 cd

Different letters along the column indicate statistical differences among species or treatments at p < 0.05.