Plant Protection: Entomology, Plant Pathology, and Integrated Pest Management
Plant Protection combines insect pest identification, disease diagnosis and Integrated Pest Management. The exam expects you to distinguish damage from disease, use thresholds, and choose safe, legal control measures.
Core concepts
- Chewing pests remove tissue; sucking pests withdraw sap and may transmit viruses. Borers feed inside stems or fruits, so symptoms may appear late.
- The disease triangle requires a susceptible host, a virulent pathogen and a favourable environment. Control can target any side of the triangle.
- IPM uses cultural, mechanical, biological and chemical tools in that order where feasible. It is not chemical-free farming; pesticides are a last resort within the programme.
- Economic threshold level (ETL) is the pest density at which control is justified to prevent reaching the economic injury level. Scout fields rather than spray by calendar.
Worked example
A label recommends a 0.1% product spray and the spray volume is 200 L. 200 L of water weighs about 200,000 g. Product needed = 0.1 ÷ 100 × 200,000 = 200 g. If the formulation is 50 WP, the active ingredient applied is 50% of 200 g = 100 g. Reasoning: first calculate product from the dilution, then active ingredient from the formulation percentage. State both if the question asks for a.i.
Traps that cost marks
Do not confuse a sign (pathogen structure or insect) with a symptom (plant response). Do not equate ETL with economic injury level. Observe pre-harvest interval and label directions. Repeated use of one mode of action selects resistance, so rotate groups. Do not recommend a broad-spectrum spray before scouting.