Plant Protection and Integrated Pest and Disease Management
Domain 7 tests diagnosis and integrated management of pests and diseases. The exam favours scouting, thresholds and safe pesticide use over blanket spraying.
Core rules
- The disease triangle requires a susceptible host, a pathogen and a favourable environment. Remove any one and disease is reduced.
- Identify the pest or pathogen before choosing a control. Leaf spots, wilts, viruses and nutrient deficiencies can look similar.
- Integrated pest management uses cultural, mechanical, biological and chemical methods in a planned sequence.
- Cultural methods include clean seed, resistant varieties, crop rotation, sanitation and optimum spacing.
- Biological control uses natural enemies such as predators, parasitoids and microbial agents.
- Chemical control requires the correct product, dose, timing and coverage. Rotate modes of action to slow resistance.
- Observe the pre-harvest interval and wear protective equipment. Never mix incompatible products.
Worked example
A vegetable grower sees yellowing between leaf veins while veins remain green. This pattern suggests a nutrient deficiency, especially iron or magnesium, rather than a leaf-spot disease. A fungal leaf spot usually shows dead spots, margins or concentric rings. The grower should inspect the whole field and soil test before spraying a fungicide. Spraying a fungicide for a deficiency wastes money and does not correct the cause.
Traps that cost marks
Do not treat every spot as fungal. Do not spray above the label dose. Do not ignore the pre-harvest interval. Do not rotate products with the same mode of action and call it resistance management.