Efficacy Of Tillage Weed Control For Vegetable Brassicas

Weed control is a major reason normally advocated for soil tillage. The use of primary cultivation, ploughing and secondary cultivation, discing and harrowing eliminates emerging annual weeds and suppresses perennial weeds. Ploughing buries about 80% of surface weed seeds and only returns about 40% to the surface. It also brings perennial rhizomes and tillers to the surface, allowing them to be killed by desiccation or freezing.

Conservation (limited) tillage or non-tillage systems have been advocated for oilseed brassicas, but are less frequently used for high-quality vegetable cole crops. The presence of crop residues on the surface tends to slow down the processes of soil warming, provides habitats for pests and pathogens, and may encourage the development of perennial and groundkeeper weed populations. Flame weeding has been used for selective control and the removal of crop residues applied prior to crop emergence in countries such as the USA. These systems are particularly suited to crops that emerge slowly. Hand weeding is largely discarded except as a labour-intensive and consequently expensive supplement to other strategies and when applied only as an emergency measure.

The side effects of mechanical weed control in Brassica production are that in addition to the intended effects on weeds, mechanical control causes some negative side effects such as physical damage to crops. A positive effect could be improved soil structure. Studies in cauliflower showed that where there was an overall treatment, this resulted in at least 4% loss of plants with ridging and tine harrowing. Yields of mechanically controlled crops ranged between 82 and 111%, with an average of 97% of untreated control (Laber and St├╝tzel, 2000).

0 0

Post a comment