Occurrence of different weeds in canola: a survey of farmers in District Swat-Pakistan.

A survey of farmers was conducted in District Swat to Pakistan record losses due to weeds in canola production. A total of 100 farmers from 5 villages were randomly selected and interviewed by using a structured questionnaire. Seventeen weeds were reported as problem weeds in the region. According to the survey, these weeds cause 2030% losses in canola production. Overall, 51% of the farmers regard weeds as the most important constraint related to canola production. Almost none of the farmers control weeds chemically, 35% reported mechanical control, whereas 65% of the farmers do not control weeds. Majority of the farmers considered that infestation of canola by weeds increased over the last ten years. According to the farmers’ reports, canola yield ranged from 1600-2400 kg ha -1 . Major weeds found in canola were Synapsis arvense, Chenopodium sp., Convolvulus arvensis, Rumex sp., Coronopus didymus. Among parasitic weeds, Orobanche was recorded as a serious weed in canola and tobacco, causing up to 50% losses.