Pest Identification and Integrated Pest Management
Identify before you act
The first IPM step is correct identification: insect versus mite versus disease versus nutrient injury versus herbicide symptom; grass versus broadleaf weed; and the species, because thresholds and control options differ. Use a hand lens, know the host plant, and know which life stage actually causes damage - many insects damage only as larvae or nymphs.
The IPM pyramid
Cultural controls (rotation, resistant varieties, sanitation, planting date), mechanical and physical controls, biological controls (predators, parasitoids, pathogens), and finally chemical control as the most targeted tool. Monitoring - scouting, sweep nets, sticky cards, weed counts - drives decisions, and thresholds convert counts into action.
- Economic threshold: the pest density at which treatment returns more than it costs.
- Economic injury level: the density causing loss equal to treatment cost (always at or above the threshold).
Resistance management
Resistance develops fastest under repeated use of one mode of action. Rotate IRAC, HRAC, or WSSA groups (the group number or letter is printed on the label), use full labeled rates, and avoid sublethal doses. Trap: tank-mixing two products with the same mode of action is not rotation.
Worked example
Treatment costs $18 per acre; the crop is worth $4 per bushel; scouting predicts a 6 bu/A loss if untreated. Six bushels times $4 equals $24, which exceeds $18, so treat. If the predicted loss were 3 bu/A ($12), the threshold is not met - do not treat.
Traps
- Calendar spraying 'because it is that time of year.'
- Treating beneficial insects as pests.
- Confusing disease symptoms with insect damage and buying the wrong product class.