How to fight the kidney tick on currants in spring? - briefly
Treat the plants with a dormant oil spray before bud break, then apply a spinosad‑based bioinsecticide at the first sign of activity and prune out heavily infested canes. Keep the canopy open and monitor regularly to limit humidity and further infestations.
How to fight the kidney tick on currants in spring? - in detail
The kidney tick (Eriophyes vitis) attacks blackcurrant shoots and leaves early in the growing season. Adult females emerge from overwintering sites as temperatures rise above 10 °C, lay eggs on tender tissue, and cause deformation that reduces yield. Early detection and prompt action are essential because populations expand rapidly during spring.
Cultural measures reduce initial infestations.
- Remove and destroy all fallen leaves and pruned material before buds break.
- Prune out heavily infested shoots during dormancy; cut at least 20 cm below the affected area.
- Space plants at least 1.5 m apart to improve air circulation and limit humidity, which discourages mite development.
- Plant resistant cultivars when available; they exhibit fewer symptoms and lower mite reproduction.
Chemical options must be applied at the first sign of activity, before eggs hatch.
- Early‑season miticides containing abamectin, spirodiclofen, or sulfur are effective when sprayed on emerging leaves.
- Follow label‑specified rates; repeat applications at 7‑10‑day intervals until bud swell ceases.
- Rotate products with different modes of action to prevent resistance.
- Observe pre‑harvest intervals to ensure fruit safety.
Biological agents supplement cultural and chemical tactics.
- Predatory mites of the genus Neoseiulus consume kidney tick eggs and juveniles; release them when mite numbers are low.
- Entomopathogenic fungi such as Beauveria bassiana colonize leaf surfaces and infect mites; apply as a spray during cool, moist conditions.
- Soil‑borne nematodes (e.g., Steinernema feltiae) attack overwintering stages in the litter layer; incorporate them into the mulch before bud break.
Monitoring establishes the need for intervention.
- Inspect 10 randomly selected shoots per bush weekly from bud swell to full leaf expansion.
- Record the proportion of leaves showing stippling or deformed growth; an incidence above 5 % warrants treatment.
- Use degree‑day calculations (base 10 °C) to predict peak mite activity and time sprays accordingly.
An integrated program combines sanitation, resistant varieties, timely miticide applications, and biological augmentations. Consistent scouting, adherence to spray schedules, and rotation of control measures maintain the pest below economic thresholds throughout the critical spring period.