Mechanical control

Mechanical control measures include a number of procedures by which we collect and destroy pests or, with the help of various mechanical barriers, prevent them from reaching crops. Some mechanical pest control measures are carried out when the pests attack the host plant and are aimed at preserving yields, and some measures are carried out when the vegetation is dormant or when the pest does not cause direct damage to plants and is aimed at reducing the population in the future.

Mechanical measures prevent the spread of pests mechanically, and this is achieved by deep plowing of plant residues, cultivation, dusting of stubble, hoeing, handpicking, pruning branches with overwintering forms of pests or pathogens, gathering on small areas or plowing rotten fruit, removing infected leaves, destroyed plants or possible hosts, by digging canals for collecting pests, placing sticky traps on trunks, cleaning seeds and weeds, setting traps for voles and nets to protect against birds and insects, even spraying plants with a water hose to knock off aphids and mites is considered a mechanical practice.

• Destruction of plant debris

Plant debris or residues in which some pests can overwinter must be destroyed by chopping into small pieces and by deep plowing (20-30 cm). Another solution is burning; however, this method is not recommended as burning crop residues eliminates the possibility of humus improvement, and can potentially lead to significant nutrient loss. Likewise, it may affect other organisms living on or in the soil. In greenhouse production, the destruction of plant residues is necessary and may include burning of plant residues.

• Manual or machine collection and direct destruction

Hand destruction or removal of insects and egg masses ensures quick and positive control. This method is especially effective with foliage-feeding insects. Handpicking is also generally useful for the management of caterpillars, leaf rollers, tobacco caterpillar, cabbage butterfly, mustard sawfly, Epilachna beetle, white grubs etc. Excluding labor, handpicking is the least expensive of all organic or natural control practices. However, handpicking also has disadvantages in that it must be performed long before insect damage is noticeable and at the key stage of development of the insect. Farmers must actively monitor their crops, watching for the first sign of damage before insect populations get too high. Collecting pests using machinery greatly facilitates this method but it is more expensive.

• Mechanical trapping

Several types of mechanical devices are used for collecting insect pests. Corrugated cardboard banding, applied to the trunks of host trees, works as a trap for many insect larvae as they crawl on the tree in search of a place to pupate and overwinter. Banding is a useful tool that can aid in assessing the level of pests’ presence in particular trees as well as in control. Simple vessels or traps filled with water or a mixture of water and vinegar can be used in places accessible to insects. Various traps can be used for cockroaches, wasps, rodents. Adding a bait can help in attracting the pests.

• Mechanical barriers

Mechanical barriers include various types of barriers such as mechanical barriers for snails, game fences, canals for insects that come to the fields by walking, nets that are placed on windows and entrance openings of greenhouses or warehouses, nets or other materials that cover crops or are used to wrap plants. With the necessary preventive measures, weed density can be reduced, but it will hardly be enough during the critical periods of the crop at the beginning of cultivation. Therefore, mechanical methods remain an important part of weed management.

• Manual and flame weeding

Manual weeding is probably the most important one. As it’s very labor intensive, reducing weed density as much as possible in the field will bring less work later on and should therefore be aimed at. There are different tools to dig, cut and uprooting the weeds; hand, ox-drawn and tractor-drawn tools. Using the right tool can increase work efficiency significantly. Weeding should be done before the weeds flower and produce seeds.

Flame weeding is another option: Plants are heated briefly to 100°C and higher. This provokes coagulation of the proteins in the leaves and a bursting of their cell walls. Consequently, the weed dries out and dies. Although it is an effective method, it is quite expensive, as it consumes a large amount of fuel gas and needs machinery. It is not effective against root weeds.