After spraying, the tolerance of herbicides to rain varies by type. Generally, rain within a few hours after spraying may affect their effectiveness.
Some herbicides, such as Acetochlor, can withstand rain within 2 hours; others, such as Clethodim and Nicosulfuron, can withstand rain within 8 hours;
Glyphosate, can withstand rain within 6 hours. A light rain after spraying may help, keeping the leaves hydrated for better absorption. However, heavy rain, especially within 4 to 6 hours after spraying, may affect efficacy or damage the crop.
Therefore, the decision to re-spray should take into account the type of herbicide, rainfall, and timing. Moderate rain within the recommended post-spray time usually does not require re-spraying, but heavy rain afterward may.
