How can spider mites be removed from a greenhouse? - briefly
Apply horticultural oil or neem oil sprays and introduce predatory mites (e.g., Phytoseiulus persimilis) to suppress the population, while regularly cleaning debris and lowering humidity. Maintain strict sanitation and monitor plants to prevent reinfestation.
How can spider mites be removed from a greenhouse? - in detail
Effective spider mite control in greenhouse production relies on a combination of detection, cultural practices, physical removal, biological agents, and, when necessary, targeted chemicals.
Regular scouting is the first line of defense. Inspect the undersides of leaves every two to three days, looking for tiny moving specks, webbing, or stippled foliage. Record infestation levels to gauge the speed of population growth.
Cultural measures reduce mite reproduction. Maintain relative humidity above 60 % whenever possible; higher moisture interferes with mite development. Adjust temperature to stay within the optimal range for the crop, avoiding prolonged periods above 30 °C, which accelerate mite life cycles. Remove plant debris and replace heavily infested foliage promptly.
Physical removal includes washing plants with a strong jet of water to dislodge mites and webs. Follow with a mild detergent solution (1 % liquid soap) applied to leaf surfaces; the surfactant disrupts the mite’s waxy coating and causes mortality. Rinse plants after treatment to prevent phytotoxicity.
Biological control offers sustainable suppression. Introduce predatory arthropods such as Phytoseiulus persimilis, Neoseiulus californicus, or Amblyseius swirskii at recommended release rates (e.g., 1 000–2 000 predatory mites per square meter). Ensure a compatible environment: low pesticide residues, adequate humidity, and continuous food sources (pollen or factitious prey) to support predator populations.
Chemical options serve as a last resort. Select miticides labeled for greenhouse use, such as abamectin, spiromesifen, or bifenazate, and apply according to label rates. Rotate active ingredients to delay resistance development. Combine with predatory mites only after a suitable interval (typically 7–10 days) to avoid predator loss.
Integrate all tactics into an IPM program. Begin with monitoring, apply cultural and physical steps, augment with predators, and reserve chemicals for breakthrough situations. Document each action and its outcome to refine future management cycles.