**6. Mechanical weed management**

Mechanical weed management involves the physical removal of weeds from the field by hand pulling or through the use of farm tools and implements such as hand hoes, cutlasses, cultivators, choppers, mowers disks or weeders [75, 76]. Mechanical weed management is one of the oldest weed control practice. It involves the practices of primary and secondary tillage. With mechanical weed

management, weeds in fallow fields are killed and the weed seeds buried in deep soil layers where they cannot emerge. Mechanical weed control in cucumber also involves plowing or disking to destroy weeds by exposing them to variations in light, moisture and temperature [77]. Secondary tillage practices such as harrowing is also used to dislodge and shred weeds in cucumber field. Although these practices destroys weed quickly, they do not provide season-long effect because some weed seeds are still present close to the soil surface [77]. It is therefore imperative to use mechanical weed management before or during early flowering to prevent the production of large quantity of weed seed, and engage follow-up weed control practices to achieve effective weed control. The best practice is usually to cultivate cucumber at the preliminary stage of weed growth when the weeds are still physiologically immature to exert significant competition with the crop [65]. Mechanical weed control cannot be used as the singular method of weed management because it may provide favorable conditions for emergence and dispersal of dormant weed seeds. It also impact the soil structure negatively resulting in soil dryness and compaction [65]. Hence, mechanical weed control must be used only as a supplement to other weed control practices within the context of integrated weed management.
