I agree on the iron phosphate vs. the nasty chemical stuff that will kill non-target species. I don't actually use the \"sluggo\" brand, but something else with the same active ingredient. Puts the hurts to those slugs and snails!
Now the Deadline That I use does last through 5-6 inches of rain. It is called Deadline MP's and is blue in color. The smallest bag is 10 lbs and Mfg by Amvac, Not the same asthe stuff made br Corry's co.
I went out and checked what I have. It is an iron phosphate based \"green\" product made by Ortho. Granted, I'm only using it on my \"backyard\" patches, so am not using large quantities out on my woods patches. (The woods patches don't seem to be a problem.) One thing I like about using an iron phosphate product is that there are no persistent chemicals soaking into the ground and being taken up into the roots. I get more $$ when I sell my roots as \"organic,\" which the iron phosphate products fall within.
The main thing is that folks should use whatever works best for them in their own situation. Doing NOTHING is the only mistake, in my mind.
Deadline MP's is the product I use in the woods. Like Classicfur said it will hold well for up to 5 or 6 rains and last longer than anything I have tried thus far with the best results as well. I can promise you that two growers that I talk to often and that I would refer to as experts are using the Deadline MP's blue pellets as well.
I looked up Sluggo and it looks like a good product too. I am just not as familiar with it as I am the Deadline MP's. Here is the link to Sluggo that I had checked out thou.