How and with what should strawberries be treated for mites? - briefly
Effective control of strawberry spider mites requires applying a registered miticide—such as abamectin, spinosad, or sulfur spray—and integrating cultural measures like pruning heavily infested leaves, ensuring adequate plant spacing, and maintaining low humidity to limit mite reproduction.
How and with what should strawberries be treated for mites? - in detail
Strawberry crops suffer significant yield loss when spider mites, two‑spotted spider mites, or broad mites infest the foliage. Effective control requires accurate identification, monitoring, and a combination of cultural, biological, and chemical measures.
The first step is scouting. Examine the underside of leaves for tiny moving specks, webbing, or stippled damage. Use a hand lens to confirm the presence of mites. Record the number of mites per leaf; thresholds of 5–10 mites per leaf typically justify intervention.
Cultural tactics reduce population buildup:
- Remove weeds and plant debris that shelter mites.
- Maintain optimal irrigation; avoid prolonged leaf wetness that encourages fungal pathogens but does not affect mites.
- Rotate strawberry varieties with known mite resistance.
- Apply mulch to moderate soil temperature and limit mite migration from the ground.
Biological agents suppress mite numbers without residue concerns:
- Phytoseiulus persimilis – predatory mite released at 10 ♀ per m²; effective against spider mites.
- Neoseiulus californicus – generalist predator, tolerates higher temperatures.
- Aphidius spp. – useful where aphids and mites coexist, as aphid predators may also consume mite eggs.
- Entomopathogenic fungi such as Beauveria bassiana – applied as a foliar spray; infection requires high humidity.
Chemical options should be reserved for severe outbreaks and integrated with non‑chemical methods to delay resistance:
- Abamectin (0.5–1 ml L⁻¹) – contact and stomach poison; withdraw before harvest according to label.
- Spirodiclofen (0.05 % SC) – systemic action; rotate with other modes of action.
- Bifenthrin (0.1 % EC) – pyrethroid; use sparingly to preserve beneficial mites.
- Sulfur dust or liquid (1–2 kg ha⁻¹) – contact acaricide; effective against broad mites.
Application guidelines:
- Treat early in the season when mite numbers first exceed the threshold.
- Apply sprays in the early morning or late afternoon to reduce photodegradation.
- Ensure thorough coverage of leaf undersides; use a fine‑mist nozzle.
- Observe a pre‑harvest interval (PHI) as specified on each product label.
- Alternate products with different active ingredients to prevent resistance.
Monitoring after treatment is essential. Re‑inspect foliage 3–5 days post‑application; if mite counts remain above threshold, consider a second application of a different mode of action or augment with additional predatory mites.
Integrated pest management (IPM) for strawberries involves the sequential use of the above tactics: start with sanitation and resistant cultivars, augment with biological control agents, and employ chemicals only when economic injury levels are surpassed. This approach maximizes yield while minimizing pesticide residues and environmental impact.