Pest Identification and Integrated Pest Management
IPM as a decision process
Integrated Pest Management combines cultural, mechanical, biological, and chemical tactics, but its core is monitoring and thresholds, not a specific product. Know the sequence: prevent, identify, monitor (scout), compare to threshold, treat with the least disruptive option, and evaluate. The action threshold is the pest density at which treatment prevents unacceptable damage; the economic injury level is the density where damage equals control cost. Treating below threshold wastes money and selects for resistance.
Identification skills tested
- Insects: chewing mouthparts (defoliation, holes) versus piercing-sucking (stippling, curling, honeydew). Complete metamorphosis (larva and adult look different) versus incomplete. Mites are not insects (eight legs, no antennae).
- Weeds: grasses versus broadleaves versus sedges - "sedges have edges," grasses have hollow round stems and ligules/auricles.
- Diseases: distinguish symptoms (plant response) from signs (mycelium, spores, bacterial ooze). Fungi cannot be controlled with bactericides.
Resistance and ecological traps
Pests develop resistance fastest with repeated use of one mode-of-action group (IRAC, HRAC/WSSA, FRAC codes). Rotate groups. Broad-spectrum sprays can trigger secondary pest outbreaks and resurgence by killing natural enemies. Distinguish this from resistance, where the same pest survives a correctly applied, previously effective rate.
Worked example: a sweep-net threshold of 1 caterpillar per sweep; 100 sweeps yield 145 caterpillars. That is 1.45 per sweep - above threshold, so treat. If counts were 60 (0.6 per sweep), no treatment; re-scout in a few days.
Biological and cultural controls only count if you can name them: resistant varieties, crop rotation, sanitation, beneficial releases, and conservation of predators.