Plant Protection (Entomology and Plant Pathology)
What this domain tests
Plant Protection combines entomology and plant pathology. The exam tests pest recognition, damage symptoms, disease symptoms, the disease triangle, economic threshold level (ETL), integrated pest management (IPM), pesticide formulations, dose calculation and safe use.
Core rules and concepts
- Chewing pests remove leaf tissue and cause holes; sucking pests remove sap and cause yellowing, curling or honeydew. Correct diagnosis decides the control method.
- The disease triangle requires a susceptible host, a virulent pathogen and a favourable environment. Removing any one leg reduces disease.
- ETL is the pest population at which control is economically justified; spraying below ETL wastes money and encourages resistance.
- IPM combines cultural, mechanical, biological and chemical methods, with chemicals as the last resort.
- Fungicides and insecticides are used at the recommended concentration and spray volume; the pre-harvest interval must be respected.
- Do not mix incompatible products, and do not spray in strong wind or immediately before rain.
Worked example
A recommendation is 2 mL of formulation per litre of spray, and the crop needs 500 L of spray volume per hectare. For 0.4 ha, spray volume = 500 × 0.4 = 200 L. Formulation needed = 2 × 200 = 400 mL. The reasoning is: first find the total spray volume for the actual area, then multiply by the dose per litre. Confusing dose per litre with dose per hectare is a common error.
Traps that cost marks
Do not identify a disease from one leaf without checking the pattern of spread. Do not call a deficiency symptom a disease. Do not use the same insecticide repeatedly against the same pest. Do not state a waiting period without checking the label. Do not calculate spray volume for the whole hectare when the question gives a smaller plot.