Good weather conditions for treatment
Weather conditions for effective spraying of plant protection products.
Acceptable wind presence for spraying plant protection products
Spraying is prohibited (Decree of 12/09/2006 relating to the marketing and use of plant protection products) if the wind speed is greater than 3 on the Beaufort scale, which corresponds to a gentle breeze of 12 to 19 km/h; leaves and small branches are constantly moving.
Ideally, during spraying, the wind should not exceed 2 on the Beaufort scale, that is a light breeze of 6 to 11 km/h because from 12 km/h wind drift becomes significant and a significant part of the spray mixture, thus the product, does not reach its target.
Humidity suitable for successful plant protection treatment
Ideally, spraying is done at more than 80% humidity; plant cuticles are dilated which ensures good product efficacy.
Treatment is possible with humidity between 60% and 80%.
Below 60%, product absorption by plants is poor and the spray mixture risks crystallizing, so intervention should be avoided.
Temperature range to ensure the effectiveness of plant protection products
From 8°C to 20°C or even 25°C, weather conditions are good for effective treatment.
A temperature below 8°C or above 25°C affects the plant (contracted cuticle…) and generally makes the products less effective.
Dew point
In the absence of dew, check the humidity; it is unlikely that conditions are good for treatment.
In the presence of dew, you can tap the leaf of the targeted plant:
- If water runs off: wait to treat because the spray mixture will also run off.
- A "heavy" dew (1 mm) that wets your knees corresponds to 10 m³/ha;
- If water does not run off: treatment is possible.
- Dew redistributes the spray mixture if it is not run-off, thus making the treatment more effective.
