Q: We received two similar questions that have been answered together.

I managed to apply my winter pre emergent two days before Hurricane Ivan dumped his generous rainfall on my lawn. Was the application in vain?

A: Actually, there should be no worries in either situation. Turf fertilizers are designed to release their nutrients over several weeks: water flowing over the fertilizer granules only dissolves a little of the fertilizer at a time. If the granules themselves washed down the hill there would be a problem but I doubt that happened. They are so small that they are likely still nestled at the base of the grass plants.

Pre-emergent herbicide granules, on the other hand, are designed to dissolve rapidly and stay put. My bet is that the chemical dissolved into the ground during the first half-hour of rain and still remains there. I would not re-apply a pre-emergent.