What should be done about spider mites on plants? - briefly
Control spider mites by promptly applying horticultural oil or neem oil and regularly washing foliage to remove eggs and larvae. If the infestation continues, introduce predatory mites or use insecticidal soap as a targeted treatment.
What should be done about spider mites on plants? - in detail
Spider mites are tiny arachnids that feed on plant sap, causing stippling, yellowing, and leaf drop. Early detection relies on inspecting the undersides of leaves for fine webbing and moving specks. A magnifying lens or hand lens improves accuracy.
Identification and monitoring
- Examine foliage weekly, especially during hot, dry periods when populations surge.
- Count mites on a sample leaf; thresholds of 5–10 mites per cm² often justify intervention.
- Record observations to track population trends and assess treatment efficacy.
Cultural practices that reduce infestations
- Maintain adequate humidity; misting or using a humidifier lowers mite reproduction rates.
- Avoid excessive nitrogen fertilization, which produces tender growth favored by mites.
- Prune heavily infested shoots to eliminate breeding sites and improve air circulation.
- Rotate crops or repot indoor plants with fresh, sterile media to disrupt life cycles.
Biological control agents
- Predatory mites (e.g., Phytoseiulus persimilis, Neoseiulus californicus) consume large numbers of spider mites; release them when mite densities exceed the economic threshold.
- Entomopathogenic fungi such as Beauveria bassiana infect and kill mites; apply according to label directions, ensuring leaf surfaces remain moist for several hours.
- Ladybird beetle larvae and lacewing larvae provide supplemental predation, especially in greenhouse environments.
Chemical options for severe outbreaks
- Insecticidal soaps and neem oil act as contact acaricides; spray until runoff, covering both leaf surfaces.
- Synthetic miticides (e.g., abamectin, bifenthrin) should be reserved for resistant populations; rotate active ingredients to delay resistance development.
- Follow label rates, re‑apply after 7–10 days if mite counts remain above threshold, and observe pre‑harvest intervals.
Preventive measures for long‑term management
- Quarantine new plants for at least two weeks, inspecting for mites before introduction.
- Clean tools and containers with alcohol or bleach solutions to avoid cross‑contamination.
- Use reflective mulches or aluminum foil barriers in outdoor beds to deter mite colonization.
- Implement a regular schedule of mild miticide applications (e.g., horticultural oil) during peak seasons to keep populations below damaging levels.
Safety considerations
- Wear protective gloves and eye protection when handling soaps, oils, or synthetic chemicals.
- Store products in labeled, child‑proof containers away from food areas.
- Dispose of heavily infested plant material in sealed bags to prevent mite spread.