Q. 34.0( 3 Votes )

Visit a nearby crop field and collect information regarding techniques of removal of weeds and chemical control of insect pests.

Answer :

The different techniques for the removal of weeds are:

Digging out plants: Plants with bulbs, tubers and corms must be completely removed from the soil by digging out. Often these plants will reproduce from broken off pieces.

Crowning: This technique is useful for weeds such as asparagus fern, which have their growing points below the surface of the soil. (corms, rhizomes or tufted fibrous root systems).

Hand pulling: This requires holding the plant stem as close as possible to the base of the plant. Gently tug the plant. This will loosen the soil and allow the plant to come free. The plant may be hung up off the ground or piled in a heap.

Winding up: This process is suitable for plants with surface or climbing runners such as Morning glory.

Foliar Spraying: Foliar sprayingis a complementary or alternative method to some hand removal techniques. It is used in large areas of weed infestations that have a small native component or small dense areas of weeds with no natives. There are three different spraying techniques.

Cut, Scrape and Paint (Cut Stump):This process is suitable for coppicing and suckering weeds such as Camphor and Privet, or any weeds which are too large for hand-pulling or have long taproots such as Ochna. This method provides for no soil disturbance and weed eradication is successful.

Types of insect control that are used for insect prevention can be categorised into

● Cultural

● Mechanical/Physical

● Biological

● Genetic

● Chemical

Mechanical/ Physical method

This includes the simple fly swat, fly screen and mosquito nets, light traps ('zappers'), exclusion methods such as packaging and sealing . It also includes drainage against mosquitoes and removal of bushes against tsetse flies.

Biological Method

This includes the application of available predators, parasites or diseases, either natural, introduced or commercially available.e.g. Introduction of spray applications of bacterial diseases against caterpillars.

Genetic method

This includes male sterilisation techniques, selective breeding and genetic modification.

Male sterilisation techniques involve the mass rearing of a pest, laboratory sterilisation of males and their release into the wild with the purpose of swamping the wild male population leading to infertile egg laying.

Chemical Method

Chemical control includes Antifeedants - prevent an insect from feeding and it starves, Anti Oviposition chemicals - females won't lay eggs and repellents - e.g. personal fly repellents

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