Pest Identification and Management
Diagnose before you spray
Every management decision starts with correct identification. Insects are separated by feeding habit: chewing pests (caterpillars, beetles) make holes and skeletonize, while piercing-sucking pests (aphids, leafhoppers, true bugs) cause stippling, curling, and honeydew. Mites are not insects; adults have eight legs and cause fine bronzing or webbing. Weeds are keyed by leaf venation, nodes, ligule, auricles, and collar region to separate grasses from broadleaves, and by life cycle (annual, biennial, perennial) because perennials usually need systemic products and repeated timing. Plant diseases follow the disease triangle: susceptible host, virulent pathogen, and favorable environment must all be present.
Integrated pest management
Scout on a defined pattern, record counts, and compare with the economic threshold, the pest density at which treatment prevents loss equal to control cost. Treat at threshold, choose the least-risk effective option, and rotate mode-of-action groups to slow resistance. Resistance shows as a product that used to work now failing on the same pest under the same conditions; repeated use of one group is the usual cause.
Traps
- Confusing pest damage with herbicide injury, nutrient deficiency, or drought stress.
- Treating on a calendar rather than at threshold.
- Repeating one mode of action until it fails.
- Scouting only once, early, and missing a second generation.
Worked example
You sample 100 leaves in a potato field and find mites on 12; the threshold is 10 percent of leaves infested. Count is above threshold, but you also find high predator-mite numbers, so you re-sample in three days before deciding. Thresholds are guidance, not an automatic trigger.