Crop Protection: Pests, Diseases and Weeds
What the domain tests
Crop Protection tests identification and management of insect pests, diseases and weeds, with emphasis on integrated pest management (IPM), economic thresholds and safe pesticide use.
Core rules
- Insect pests include chewing types (caterpillars, beetles) and sucking types (aphids, jassids, whiteflies). Sucking pests remove sap and may transmit viruses.
- Disease develops from the interaction of a susceptible host, a virulent pathogen and a favourable environment - the disease triangle. Diseases may be fungal (blight, rust), bacterial (wilt) or viral (mosaic).
- Weeds are classified as grasses, sedges and broadleaf plants; sedges have triangular stems and are not controlled by ordinary broadleaf herbicides.
- IPM combines cultural, mechanical, biological and chemical methods, with pesticides as a last resort.
- Economic threshold level (ETL) is the pest population at which control is justified to prevent economic loss.
- Follow label dose, protective clothing, safe interval before harvest (PHI) and correct disposal.
Worked example
A field has heavy broadleaf weed growth, but the crop is a grass-like cereal and sedges are also present. Reasoning: a selective broadleaf herbicide may control the broadleaf weeds but will not control sedges. Confirm weed identity first; for sedges, mechanical removal or a suitably labelled herbicide may be needed. Do not spray a non-selective herbicide over a standing crop.
Traps
Not every insect is a pest; natural enemies should be conserved. Do not spray below ETL. Do not assume one fungicide controls all diseases. Herbicide drift can damage neighbouring crops. Always check crop stage, label and PHI.