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OMAFRA: Timing fungicides around frequent rains

Timing fungicides can be a challenge, especially with frequent heavy rains. Infection for most diseases requires rainfall.

Fungicides are used mostly protectively and thus work best if applied before rain. But how well do fungicides stand up to rains that occur after application?

Avoid putting on fungicides within several hours before a rainstorm as much can be lost to wash-off regardless of formulation. When considering any foliar fungicide, the time from application to the next rain event is critical. If contact or systemic fungicides were applied and a significant rain event occurs within two hours, it is very likely that a large portion of that fungicide was washed off. |READ MORE