Which condition may enhance the effectiveness of spray pesticides?

Humidity plays a crucial role in enhancing the effectiveness of spray pesticides. Higher humidity levels reduce the rate of evaporation of the pesticide solution from the plant surfaces, allowing for a more extended period during which the active ingredients can adhere to and penetrate the target pests. This increased adherence and slower evaporation help ensure that the pesticide maintains its potency longer, leading to improved efficacy against pests.

In contrast, conditions like dry and windy weather often lead to rapid evaporation and drift, reducing the amount of pesticide that reaches its target. Cloudy days can affect some types of pesticides that rely on sunlight for activation but are generally more favorable than completely dry conditions. Soil moisture, while essential for root health and nutrient uptake, doesn't directly influence the effectiveness of foliar-applied pesticides. Therefore, humidity is the most critical factor in this context for maximizing the impact of spray pesticides.