Frank I suspect that Provado mean on the plant not the soil, I'm not sure but if you do it before they hatch out in spring then after a week or so plant your crops it should be ok. It might be an idea to find out when they hatch out.

No need to use Provado at all for Vegtable crops. In 30 years of fighting the dratted things I have never seen them on any Vegetables grown in the soil. Despite what you might think, the grubs actually do not normally in open ground destroy all the roots of any plant. It is only in confined situations like a plant pot where they eat everything in sight.
Er. out of interest what are'Osters'?

Thanks Both of you. I had a senior moment, I meant HOSTAS. I think thats right.

Ta, yes Hostas do attract the blighters, don't they?
Provado remains active in the soil for up to 6 months and is NOT recommended at all for Vegetable growing.

Thanks again Owdboggy, I dont think I will use it on that bit of ground. Frank