Weed control in cauliflower ( Brassica oleracea var. Botrytis L.) with herbicides

Abstract

Field experiments were carried out to evaluate the effect of different herbicides on weeds and cauliflower ( Brassica oleracea var. Botrytis cv. White Cloud) grown under Jordan Valley conditions during the 1996/1997 and 1997/1998 growing seasons. The most common weed species were Chenopodium murale L. (133 plants m −2), Malva sylvestris L. (38 plants m −2) and Echinochloa colonum (L.) Link (13 plants m −2). On average, weed competition for the entire growing season reduced cauliflower shoot dry weight by 74.8% and head weight by 76.1% compared with the weed-free control. With the exception of linuron, all herbicide treatments increased crop shoot dry weight, head weight and number compared with the weed-infested plots. Oxyfluorfen applied pre-planting at 2.5 l ha −1 resulted in the highest cauliflower growth and head yield. Pre-planting application of chlorthal-dimethyl (10 kg ha −1), pendimethalin (4.6 l ha −1), nitrofen (1.4 l ha −1) and trifluralin (1.5 l ha −1), and post-planting treatment of oxyfluorfen (2 l ha −1) were also effective and increased head yield of cauliflower compared with other herbicides. Oxyfluorfen (pre-planting) was the best in controlling weeds and reduced their shoot dry weight by 65.5% compared with the weed-infested control. Other herbicide treatments reduced weed biomass below the weed-infested control but were variable in their effects. Although diphenamid (7.5 kg ha −1) and pronamide (2.5 kg ha −1) reduced weed growth, this effect was not reflected as an increase in cauliflower shoot dry weight or head yield. Linuron (1.7 kg ha −1) was damaging to cauliflower and reduced shoot growth and head yield.