There are 3 key factors which determine good spraying conditions:
1.The hygrometry: hygrometry must be between 60 and 95% to allow the phytosanitary product to penetrate the leaves, prevent the droplets from evaporating and avoid the sprayed plants from being burnt.
2. The temperature: each phytosanitary product has an optimal temperature range for usage. E.g., a product which is absorbed by the leaves must be applied at a temperature of between 12 and 20°C.
3. Drift: the wind speed or a poorly adjusted sprayer can cause the product to drift, which will reduce the efficiency of the spraying operation (solutions to combat drift are developed in the next question).
However, each phytosanitary product requires specific climatic conditions, which are specified on the container. Ensure that you adhere to these recommendations to get the best results from your spray products.