Plant Protection (Entomology and Plant Pathology)
Plant protection covers insect identification, damage symptoms, disease diagnosis, and safe pesticide use. The exam tests IPM logic: identify the pest or pathogen, choose the right tactic, and calculate a safe dose.
Core rules
- Insect mouthparts guide control: sucking pests (aphids, jassids) need systemic or contact insecticides; chewing pests (bollworm, cutworm) need stomach poisons or biologicals. Metamorphosis may be complete (egg–larva–pupa–adult) or incomplete.
- Plant disease triangle: susceptible host, virulent pathogen, favourable environment. Fungal diseases show spots, blights, rusts, wilts; bacterial diseases show water-soaked lesions and ooze; viral diseases show mosaic, mottling, stunting and are spread by vectors; nematodes cause root galls.
- IPM combines resistant varieties, cultural methods, biological control, mechanical methods, and need-based chemicals. Follow economic threshold level, label dose, waiting period (PHI), and protective equipment.
- Pesticide formulations: WP wettable powder, EC emulsifiable concentrate, SC suspension concentrate, dust, granule. Percentage a.i. means active ingredient, not formulation.
Worked example
Prepare 100 L of 0.05% a.i. spray from a 50% WP formulation. Required a.i. = 0.05/100 × 100 L = 0.05 kg = 50 g. Formulation needed = 50 g ÷ 0.50 = 100 g. Reasoning: first find active ingredient required, then divide by the formulation's a.i. fraction; do not use 50 g of formulation, which would give only 0.025% a.i.
Traps
Using formulation weight as active ingredient; spraying fungicide for a viral disease; confusing bacterial ooze with fungal exudate; ignoring PHI before harvest; treating all sucking pests with the same contact insecticide; releasing parasitoids without checking pesticide residues.