Plant Protection
Plant Protection tests entomology and plant pathology within integrated pest management: pest recognition, disease diagnosis, thresholds, biological control and safe pesticide use.
Core rules and concepts
- The disease triangle requires a susceptible host, a virulent pathogen and a favourable environment; time is often added. Symptoms are host responses such as wilting or mosaic; signs are pathogen structures such as mycelium, spores or bacterial ooze.
- IPM uses monitoring, cultural, mechanical, biological and chemical tactics, with pesticides as a last resort. Economic threshold level is the pest density at which control prevents damage exceeding control cost.
- Rotate insecticide modes of action to slow resistance. Conserve natural enemies; use resistant varieties, sanitation, seed treatment, pheromone or light traps, Trichoderma, NPV and Bt where appropriate.
- Pesticide dose may be expressed as active ingredient or product. Formulation concentration must be included in calculations.
Worked example
Prepare 200 L of 0.1% active ingredient spray from a 50% wettable powder. Active ingredient needed = 200 L × 0.1/100 = 0.2 kg = 200 g. Product needed = 200 g ÷ 0.50 = 400 g. Add the product to water with agitation and maintain the recommended spray volume. If the label gives product dose, do not divide by 0.50 again.
Traps that cost marks
Do not confuse signs with symptoms. Do not treat at pest presence alone; compare with ETL. Do not calculate product dose as active ingredient. Do not rotate products with the same mode of action and call it resistance management. Do not ignore disease incidence versus severity.