Weed & Pest Control

This section usually covers weed classification, important weed species, crop-weed competition, herbicide types, weed-control methods, major crop pests, Economic Threshold Level, biological control agents, and Integrated Pest Management.

A weed is commonly understood as an unwanted plant growing where it is not desired. This simple definition is important because many later topics such as competition, identification, and herbicide use build from it.

Selective herbicides mainly control certain weeds without seriously damaging the crop, while non-selective herbicides can damage or kill a broad range of plants. This distinction is one of the most repeated herbicide concepts in revision.

Pre-emergence herbicides are used around the time weeds are germinating and before they become established above the soil surface, while post-emergence herbicides are applied after weeds have already emerged.

ETL stands for Economic Threshold Level. It is the pest-population level at which control action should be taken to prevent economic loss from increasing further.

IPM is important because it brings together cultural, mechanical, biological, and chemical methods in a planned way instead of relying only on pesticides. It is one of the most frequently asked conceptual areas in pest-management preparation.

Students commonly prioritize names such as Trichogramma, Chrysoperla, and NPV because these are repeatedly used in introductory IPM and biological-control discussions.

A strong order is weed definition and classification first, then weed-control methods and herbicides, then pest concepts, ETL, and finally IPM with biological-control examples.

Most students revise this topic fastest with comparison tables for herbicide types, short definitions for ETL and IPM, and one-line notes for major weeds, pests, and biocontrol agents.