What treatment is used for mites on hydrangea? - briefly
Apply horticultural oil or neem oil to the leaves, covering both surfaces and re‑treating every 7‑10 days until mites are eliminated. For heavy infestations, use a registered miticide appropriate for hydrangea, following the product label precisely.
What treatment is used for mites on hydrangea? - in detail
Mite infestations on hydrangea require an integrated approach that combines cultural, biological, and chemical measures.
Effective cultural practices reduce mite populations by creating unfavorable conditions. Regularly water the plant at the soil level to maintain leaf humidity, as dry foliage encourages spider and broad mites. Remove dense foliage and prune back crowded branches to improve air circulation. Dispose of fallen leaves and debris where mites can overwinter.
Biological options include predatory mites such as Phytoseiulus persimilis or Neoseiulus californicus, which consume spider mite eggs and larvae. Release rates of 10–20 predators per square foot provide rapid suppression when populations exceed economic thresholds.
Chemical and semi‑chemical treatments are applied when cultural and biological methods are insufficient. Recommended products include:
- Horticultural oil applied at 1–2 % concentration, covering both upper and lower leaf surfaces; repeat every 7–10 days until mites disappear.
- Neem oil at 0.5–1 % dilution, acting as a repellent and growth inhibitor; reapply after rain.
- Insecticidal soap formulated with potassium salts of fatty acids, applied at label‑specified rates; avoid excessive use to prevent phytotoxicity.
- Sulfur dust or liquid formulations, effective against broad mites; apply in cool, dry weather to minimize leaf burn.
- Synthetic miticides containing abamectin or bifenthrin, reserved for severe outbreaks; rotate active ingredients to delay resistance development.
When using chemicals, observe a pre‑harvest interval of at least 7 days and wear protective equipment. Monitor mite activity weekly with a hand lens; cease applications once counts fall below the threshold of 2 mites per leaf.
Combining these tactics maintains hydrangea health while minimizing reliance on any single control method.