Spider mites have appeared in a greenhouse—how should they be fought? - briefly
Effective control relies on integrating regular monitoring, targeted miticides approved for greenhouse use, and biological agents such as predatory mites; maintain low humidity and adequate ventilation to deter population growth. Prompt removal of heavily infested plants and strict sanitation of equipment further limit spread.
Spider mites have appeared in a greenhouse—how should they be fought? - in detail
Spider‑mite infestations in greenhouse production demand rapid identification, regular monitoring, and an integrated control program that combines cultural, biological, and chemical measures while preserving crop health and product quality.
Accurate detection begins with visual inspection of leaf undersides for stippled discoloration, fine webbing, and moving motile stages. Sticky traps placed at canopy level provide quantitative data on population dynamics. Thresholds for action vary with crop sensitivity; a common benchmark is 5 % leaf area showing damage or more than 10 mites per cm².
Cultural tactics reduce habitat suitability. Maintain relative humidity above 60 % whenever feasible, as low humidity accelerates mite reproduction. Adjust temperature to stay within optimal crop range without exceeding 30 °C, which favors mite development. Implement a schedule of thorough cleaning between crop cycles, removing plant debris and infested material. Rotate crops with non‑host species to interrupt life cycles.
Biological agents supply targeted suppression. Predatory mites such as «Phytoseiulus persimilis», «Neoseiulus californicus», and «Amblyseius swirskii» establish quickly on foliage and consume all mobile stages. Release rates of 10–20 predators per cm² of leaf surface ensure adequate coverage. Preserve released populations by avoiding broad‑spectrum insecticides and providing pollen or alternative food sources when prey density declines.
When chemical intervention becomes necessary, select products with proven efficacy and minimal residual risk. Miticides based on abamectin, spiromesifen, or bifenazate act rapidly against eggs and larvae. Apply according to label‑specified rates, rotating active ingredients every 7–10 days to delay resistance development. Incorporate oil‑based formulations to improve coverage and smother webbing.
Resistance management integrates all control layers. Record product usage, monitor mite susceptibility through laboratory bioassays, and adjust the program when efficacy declines. Combine short‑term miticide bursts with sustained predator releases to maintain pressure on the pest population.
Sanitation measures conclude the program. After harvest, disinfect benches, trays, and ventilation ducts with a suitable detergent or steam treatment. Quarantine new plant material for at least two weeks, inspecting for early mite presence before introduction to the production area.
By adhering to a systematic approach—early detection, environmental modification, predator augmentation, judicious miticide rotation, and rigorous sanitation—greenhouse operators can suppress spider‑mite outbreaks, protect yield, and minimize reliance on chemical controls.