Introduction to Integrated Pest Management, Part 3: Mechanical and physical methods of pest control

By JAMES TABABA

The previous article discusses cultural management practices for pest control as part of the IPM (Integrated Pest Management). Here, the different mechanical and physical pest control practices will be examined as another integral part of IPM.

READ: Introduction to Integrated Pest Management, Part 2: Cultural management practices for pest control 

Mechanical and physical methods are included in the strategic options for pest control in Integrated Pest Management approach. These methods refer to any physical or mechanical practices that involve the exclusion, trapping, removal, or destruction of pests.

Mechanical methods of pest control

Mechanical pest control methods involve mechanical force or manual labor for pest eradication. Mechanical pest control also consists of blocking pests’ access to crops using barriers or nets. Here are some examples of mechanical methods of pest control:

Hand-picking of pests. Hand-picking of pests is the simplest but also laborious method of pest control. It is an effective way of pest control in a small and controlled environment like greenhouses. Adults, larvae, and eggs of pests are collected and placed into a jar with water and detergent. However, be sure to identify the pest from beneficial insects. Also, avoid touching venomous pests directly.

Collection and destruction of diseased plant parts. Clipping and pruning infested twigs and branches. Some of the insects bore holes and live inside twigs and branches. If you observe a single branch wilting, check if it has holes. Chances are there is an insect larva feeding inside.

Diseased and infected plant parts are removed to prevent the disease from further development. Be sure to disinfect the blades with alcohol and bleach each cut to prevent the spreading of the disease to healthy plants. Throw away or burn the collected diseased plant parts far away from the crops.

Exclusion of plants using screens and barriers. Mulches or ground covers, which can be composed of plastic or natural materials, are placed on the ground to prevent the growth of weeds. Keep in mind that natural mulches like rice straws or grass cuttings could be a hiding place for other pests. Plastic mulch can be made from reflective materials that repel aphids.

Copper tape or sticky tape is wrapped around the trees for trees and shrubs to prevent slugs and other crawling pests from crawling up the plants.

Nets are usually placed above young seedlings or rows of crops to avoid insect and bird damage. Nets are also used in plant nurseries and tropical greenhouses to prevent pests from entering.

Bagging fruits in paper bags or plastic keeps them away from insect pests, especially fruit flies that lay eggs on fruit. Be sure to wait for pollination to happen before bagging for crops like corn.

Traps. Yellow sticky trap is the most common trap used to control insect pests. It is effective in catching whiteflies and other small insects.

Light traps were used a long time ago before the use of chemical pesticides. It is used for mass-capturing moths and beetles. Insects are attracted to light during the night. Usually, a basin with water (sometimes with insect attractant and soap) is placed below the light to trap and collect insects.

A mouse trap captures and controls rodent pests in rice and other crops.

Water spray and irrigation. Flooding and draining of rice fields to control pests. Flooding rice fields reduces root-feeding rice weevils. During the planting stage of rice, fields are drained to prevent the emergence of snails that feed on the young rice.

Spraying leaves with water and soap solution can control aphids. The strong pressure of water usually knocks off aphids.

Physical methods of pest control

Physical methods of pest control are practices that involve altering the physical environment to reduce the pest population. Changing and controlling the temperature, the composition of air gasses, moisture, light, radiation, and sounds of the cropping and storage environment are forms of physical pest control. Here are some physical method practices:

Heat. Heating soil by burning or applying hot water will kill disease-causing fungi, bacteria, and viruses. During tillage, exposing the soil to the direct heat and radiation of the sun also kills some disease-causing organisms and soil-borne insect pests.

In mango and banana, dipping the fruits in hot water kills the fungi responsible for the black spots when they ripen.

Moisture. Decreasing the humidity within the plants and improving air circulation through pruning or removing plant parts like leaves and branches will reduce the chance of disease development.

In postharvest storage of grains, maintaining a low humidity is important in preventing disease development. 

Cold. Cold storage of fruits and vegetables prevents disease development. Some of the insects and pests are also killed in low-temperature storage. Fruit fly larvae cannot survive long exposure to cold temperatures.

Mechanical and physical methods for pest control are IPM strategies for pest control to reduce pesticide use. Though, mechanical methods are more effective in small farms. Hand-picking of pests is impractical to do in huge production areas. Installing net covers in big areas will incur large expenses. Furthermore, using traps can target non-pest insects.

The same is true with physical methods. Sterilizing soil with hot water is impossible for large production areas and cold storages are expensive.

This is why using mechanical and physical methods of pest control should be implemented together with other pest control strategies like cultural, biological, and behavioral pest control methods.

Part 4 will discuss how predators, parasitoids, pathogens, and botanicals are used in IPM as part of the biological management practices for pest control

READ: Introduction to Integrated Pest Management, Part 4: Biological methods of pest control