Evaluating glufosinate-ammonium and flame weeding for weed control in sweet marjoram (Origanum majorana L.) cultivation

Abstract

The objective of this four-year study was to compare the effects of flame weeding and spraying with glufosinate-ammonium on weed control in sweet marjoram field cultivation. The experiment was set up in a complete randomized four-replicate design with a plot area of 8 m2. Moreover, the content of essential oil in marjoram herb obtained from the control plants, as well as the composition of this oil were also studied. Marjoram emergence began 13–17 days after sowing, and it was very uneven and in some years it was extendend up to 5 weeks. Flaming (90 kg propane ∙ ha–1) was applied in two times: immediately after noticing the first marjoram emergence or 5 days later, while glufosinate-ammonium (600 g ∙ ha–1) was applied on the same date as the first flaming. The tested methods of weeding significantly reduced the number and fresh weight of weeds growing 3–4 weeks after the start of marjoram emergence, i.e. in the period of its greatest sensitivity to weed competition. They had no soil residual activity and their effect on weeds disappeared after the first weeding. Among weeds occurring in the experiment, only barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.) was partially tolerant to flaming. Flaming applied at the second time did not increase the effectiveness of weed control, but significantly decreased the number of emergence and the yield of marjoram herb. Essential oil content in marjoram grated herb varied considerably depending on the year, ranging from 1.35 to 2.34%. The oil contained from 33 to 36 identified compounds, among which trans-sabinene hydrate (28–34%) and terpinen-4-ol (17–21%) were clearly dominant.