Selectivity and efficacy of herbicides dimethachlor and pethoxamid in rocket crop

摘要

Field experiments were conducted to evaluate the efficacy, selectivity and health harmlessness of four application rates of two pre-emergent herbicides (pethoxamid and dimethachlor) in the rocket [Eruca vesicaria (L.) Cavanilles)]. Pethoxamid was found to be less efficient on the total weed density (efficacy 86.0-93.3%) in comparison with the effect of dimethachlor (94.9-95.8%). Dimethachlor expressed an excellent efficacy on Echinochloa crus-galli (L.) P. Beauvois, Portulaca oleracea Linnaeus, Amaranthus retroflexus Linnaeus, Lamium purpureum Linnaeus, and Veronica persica Poiret from the lowest tested application rate (800 g/ha). Pethoxamid showed an excellent efficacy on E. crus-galli, Lamium purpureum, Lamium amplexicaule Linnaeus, V. persica, and P. oleracea. In higher application rates, pethoxamid controlled Chenopodium polyspermum Linnaeus and Chenopodium album Linnaeus. In contrast to mostly negative effects of dimethachlor, pethoxamid showed either no effects or positive ones on the rocket yield. Residues of both herbicides in the harvested product were always below a 'default limit', which is the baseline maximum residue level for food. The selectivity of pethoxamid at an application rate of 960 g/ha was good, herbicide residues in the rocket were not detected and the yield of the rocket increased.