How to treat chrysanthemum for spider mites? - briefly
Apply a miticide—e.g., neem oil, horticultural oil, or a pyrethrin product—by spraying the entire plant, covering the undersides of leaves, and repeat every 7‑10 days until mites are gone. Remove heavily infested foliage and maintain lower humidity to prevent reinfestation.
How to treat chrysanthemum for spider mites? - in detail
Spider mites rapidly colonize chrysanthemum foliage, feeding on cell contents and causing stippling, discoloration, and webbing. Effective management requires early detection, sanitation, cultural adjustments, biological agents, and, when necessary, chemical interventions.
Inspect plants weekly, focusing on the undersides of leaves. Use a 10× hand lens to identify tiny moving dots and fine silk. Remove heavily infested leaves and destroy them away from the growing area.
Cultural practices that reduce mite populations:
- Maintain ambient humidity above 60 % during the day; low humidity favors mite reproduction.
- Space plants to allow adequate air circulation and light penetration.
- Water at the soil level to avoid wetting foliage, then mist the canopy lightly to increase leaf moisture without promoting fungal disease.
- Rotate crops and avoid planting chrysanthemums in the same location for more than two consecutive seasons.
Biological controls:
- Release predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus at a rate of 1 – 2 predators per square centimeter of leaf area.
- Apply neem oil (5 % concentration) or insecticidal soap (2–3 % fatty acid solution) every 5–7 days, covering both leaf surfaces thoroughly.
- Use entomopathogenic fungi like Beauveria bassiana according to label instructions; spray until runoff.
Chemical options, reserved for severe outbreaks:
- Select a miticide with low toxicity to beneficial insects, such as abamectin (0.5 ml L⁻¹) or spirodiclofen (0.2 ml L⁻¹).
- Apply in early morning or late evening to minimize photodegradation.
- Observe the pre‑harvest interval and rotate active ingredients to prevent resistance development.
After treatment, monitor the population for at least three weeks. Re‑apply biological or chemical controls only if mite numbers rise above the economic threshold (approximately 5 % leaf area showing damage). Maintain the preventive cultural measures to keep future infestations below damaging levels.