"IPM means using organic products instead of synthetics." With that understanding, a spinosad product and pyrethrin-based spray appear in the greenhouse — and the same logic continues: spot the pest, treat it. Just "organically" now. IPM is not swapping one product for another. It is a system where a pesticide application is the last step, not the first.
Quick glossary: IPM (Integrated Pest Management) — a pest and disease management system that combines monitoring, prevention, biological control, and chemical treatments in strict order; the goal is to keep pest populations below the economic threshold, not to eliminate every individual. Monitoring — regular, documented inspection of plants and traps that produces quantitative data on pest population status. Economic threshold — the pest population level at which economic damage exceeds the cost of control measures; below the threshold: observe. Above it: act.
How IPM Differs from "Spray and Forget"
The default logic: thrips appear — grab an insecticide, treat, thrip numbers drop. Two weeks later they're back — treat again. The problem is that this logic responds to a symptom that's already visible, by which point the population has already multiplied and partially spread. And without product rotation, resistance builds over a few cycles.
IPM works differently: not "see it, spray it" — but "I know it's there, I know how many, I know the trend." The decision to treat is based on quantitative monitoring data, not visual impression. Treatment happens if the population crosses the economic threshold. Until then: prevention and biological methods.
The difference in outcome: in a reactive system you're always one step behind. In IPM — one step ahead.
IPM Levels: from Prevention to Chemistry
IPM is not a choice between "organic" and "synthetic." It is a hierarchy of levels where each successive level is applied only when the previous one is insufficient.
Level 1 — prevention and sanitation. Physical barriers (screens on ventilation openings), quarantine for new plant material, sanitation between cycles, removal of plant debris. A pest that never enters the greenhouse is the cheapest pest to manage.
Level 2 — monitoring and early action. Yellow and blue sticky traps at standard heights, scheduled crop scouting along fixed routes, counting individuals and logging results. Goal: detect an outbreak early while the population is small.
Level 3 — biological control. Beneficials — predatory insects and mites that feed on pests: Amblyseius cucumeris against thrips, Phytoseiulus persimilis against spider mite, Encarsia formosa against whitefly. Biological control is effective at low to moderate pest populations — it cannot keep pace with an established outbreak.
Level 4 — supplemental products. Insecticidal soaps, oils, and microbial products (Bacillus thuringiensis, Beauveria bassiana) — when population exceeds the threshold but biological control can still manage it with support.
Level 5 — chemical treatments. Synthetic insecticides and fungicides — when the economic threshold is exceeded and other levels no longer deliver results. Rotation of mode-of-action groups is mandatory: no more than two consecutive applications from the same group.
Monitoring: What to Record and How
Traps without counts are decoration. Real monitoring: pull traps once a week, count individuals by species, log the data. The trend — population rising or stable — matters more than the absolute number.
Scouting route: walk the greenhouse on a fixed path, inspect the undersides of leaves (thrips, mite, whitefly), growing tips (aphids), and the root zone (soil pests). Minimum 10% of plants per route; results go in the log.
Without a log there is no trend. Without a trend there is no basis for a decision. "Seems like more than before" is not data.
Three Mistakes That Cost the Most
Releasing beneficials during an outbreak. Biological control is a preventive tool and a support measure at low populations. Releasing Phytoseiulus into a heavy spider mite infestation is a waste: the predator will not reproduce fast enough before the pest destroys the crop. Reduce the population with chemistry first, then introduce beneficials to maintain control.
Applying products "preventively" without monitoring data. Regular treatments "to stop problems before they start" is not IPM, and not prevention in the IPM sense. It is chemical load without justification and the path to resistance. Prevention in IPM means sanitation and physical barriers — not chemistry.
Not rotating product groups. Spinosad twice in a row, then again — within a few generations, thrips no longer respond. Rotation of modes of action (IRAC codes for insecticides, FRAC codes for fungicides) is mandatory across every treatment series.
How to Know the IPM System Is Working
Pest populations are known quantitatively from monitoring logs and do not exceed the economic threshold for more than one consecutive week. Beneficials are present and active. The number of chemical treatments per season decreases compared to the previous year without an increase in damage. No resistance — products with the same mode of action are not applied more than twice in a row.
For deeper understanding: Beneficial Insects: Which Predators Target Which Pests — and How Not to Kill Them with Chemistry — explains how the biological level of an IPM system works in practice, and which mistakes eliminate beneficials before they have a chance to take effect.