When to spray grapes for mites?

When to spray grapes for mites? - briefly

Apply miticide at the first detection of spider‑mite colonies, usually in early summer after flowering and before veraison, then repeat 7–10 days later if populations persist. Timing should align with warm, dry conditions that favor mite development.

When to spray grapes for mites? - in detail

Mite control in vineyards depends on precise timing aligned with the pest’s development and vine phenology.

The first spray should be applied when the first juvenile stages (egg or larva) appear on the underside of leaves, typically around the bloom stage (BBCH 60‑65). At this point, leaf‐miners have not yet caused significant damage, and the mite population is still low enough for chemical intervention to be effective.

A second application is required as the population builds, usually when 5‑10 % of the foliage shows mite symptoms. This corresponds to early fruit set (BBCH 71‑73). Spraying at this threshold prevents exponential growth and reduces the risk of severe infestation during berry development.

A third spray may be necessary if monitoring indicates a resurgence after the first two treatments, especially in warm, dry seasons that accelerate mite reproduction. Apply this treatment before veraison (BBCH 81) to protect the ripening cluster from mite‑induced stress.

Key factors for scheduling applications:

• Temperature: Apply when daytime temperatures are between 15 °C and 30 °C; extreme heat reduces product efficacy.
• Rainfall: Avoid spraying if more than 2 mm of rain is forecast within 24 h, as wash‑off will diminish coverage.
• Vine growth stage: Target periods when new leaves are expanding, providing fresh feeding sites for mites.
• Resistance management: Rotate active ingredients with different modes of action; follow label‑specified pre‑harvest intervals.

Monitoring protocol:

1. Select 10 random vines per hectare.
2. Examine the underside of the 5th‑7th leaf from the shoot tip.
3. Count mites per leaf; record the average.
4. Use the following thresholds:
   • <2 mites/leaf – no spray.
   • 2‑5 mites/leaf – first spray.

   • 5 mites/leaf – second spray.

By adhering to these timing guidelines, growers can minimize mite pressure while reducing unnecessary chemical applications.