Pest Identification, Biology, and Integrated Pest Management
IPM as a decision framework
IPM is not a single tactic; it is a sequence: identify the pest, monitor and assess, set an action threshold, choose tactics (cultural, mechanical, biological, chemical), and evaluate results. Know that thresholds are economic or aesthetic-below threshold, no pesticide is justified. Traps, degree-day models, and scouting are monitoring tools. A candidate must distinguish key pest groups: insects (chewing vs. piercing-sucking, complete vs. incomplete metamorphosis), weeds (grasses vs. broadleaves, annual/biennial/perennial), plant pathogens (fungi, bacteria, viruses, nematodes), and vertebrates.
Identification matters
Misidentification leads to the wrong product and resistance. Recognize that piercing-sucking insects (aphids, whiteflies) require contact or systemic products, while chewing insects may be controlled with stomach poisons. Weed identification hinges on leaf arrangement, ligule presence, and growth habit. Disease diagnosis often requires lab confirmation; do not assume a fungus when symptoms could be viral or abiotic.
Resistance and traps
- Treating below threshold "just in case"-wastes money and selects for resistance.
- Using the same mode-of-action repeatedly; rotate IRAC/HRAC/WSSA groups.
- Confusing beneficial insects with pests; killing natural enemies can worsen outbreaks.
- Assuming one product controls all life stages (eggs vs. adults differ).
Worked example
A scout finds 3 aphids per leaf; the threshold is 10. The correct action is to continue monitoring, not spray. If counts reach 10, choose a product with a different IRAC group than the last application. Rule of thumb: no threshold, no spray-and always rotate modes of action.