Pest Identification, Biology, and Management
Know the pest before you treat it
Accurate identification drives every later decision: the product, the rate, the timing, and whether a pesticide is even needed. Candidates should be able to separate insects from mites, distinguish chewing damage (missing tissue, holes, notched leaves) from piercing-sucking damage (stippling, yellowing, honeydew, sooty mold), and recognize weeds by lifecycle (annual, biennial, perennial) and by grass vs. broadleaf. Plant disease questions usually hinge on the disease triangle: a susceptible host, a virulent pathogen, and favorable environment must all be present.
Management concepts to master include economic threshold (treat only when pest numbers justify the cost and risk), action threshold, and the foundation of integrated pest management (IPM): cultural, mechanical, biological, and chemical tactics used together. Understand resistance management - rotating modes of action and not relying on one product - and why treating beneficial insects or pollinators carelessly backfires. Know that perennial weeds regrow from underground structures and usually need systemic products and repeated effort, while annuals are best hit young.
Trap: questions that describe "yellowing leaves" and expect a single answer - yellowing can be nutrient deficiency, root damage, or sucking insects. Match the pattern of damage and the site conditions before choosing a pest. Another trap is confusing threshold with zero tolerance; most agricultural pests have a tolerance level.
Rule of thumb: scout in a pattern (W or zigzag), sample several locations, and record counts - decide with numbers, not with one bad-looking plant.