Plant in a different place, then immediately use row cover.

thanks jean but we just put this garden in using 3yr old compost and we are limited to space. would some ash from a fire pit spread around help?

Wireworms and the other wee critters that tend to do that only do so in soils that are not yet in the condition they should be, like yours that is in the first, second, or maybe even the third year. As you get sufficinet quanities of organic matter in the soil and the soil Food Web gets working well they will help control those pests for you. What you need to do is work at getting a well balanced soil, which might possibly, maybe, could include adding wood ash or it might not, depending on what a good, reliable soil test tells you.

Perhaps he has cabbage maggot (a fly) instead of wireworms. In that case, floating row cover would help. But if it is cabbage maggot, the ground is now infested.

But no, ash won't help.