Root weevil? That's a new one on me. I've never heard of anything bothering Hosta roots except voles. What are you using nematodes for? I assume you are talking about beneficial nematodes. Are you talking about white grubs?

Steve

Steve- I call them "notch bugs". The adult weevil eats notches in camelias, rhodys , aspidistra, lirope and everything else I like. These plants are evergreen around here, and probably for the OP, so the damage remains for years. The larvae eat the roots and crowns of plants, especially strawberries. Probably more of a problem in areas that don't have hard freezes that penetrate several feet down into the soil. We might have perfect weather, but that also brings some special bugs. ;-) You guys don't have to worry about soil termites either.

Beneficial nematodes need the soil temp to be over 50 (from what I've heard locally). In the ground they should last a couple years or so, or until they no longer have grubs to eat. I doubt ammonia would do anything to the grubs w/o totally soaking the soil and likely killing/harming the plants.

Where I don't use nematodes, I go for the chemicals. Bayer.

-Babka

Babka,

Do they "notch" your Hosta leaves? The information I see on line mentions, Olive Trees, Liliacs, Rhodies, and Strawberry Plants, but not Hosta. Most of the info is from extension services on the West Coast. We do get Black Vine Weevil occasionally here in the East, but they don't bother Hosta.

BTW, Predatory Ground Beetles like to eat Root Weevils as well as slugs. One of the best habitats for Ground Beetles is wood chip mulch. They like a chunky mulch with lots of air spaces.

You are, of course, correct about Beneficial Nems. The variety called Heterohabditis is said to work. Soil must be 52* or higher to be applied and moist.

Ammonia won't work on these guys, since they're beetles.

Steve

never heard of it ...

its also used on soft bodied things that ooze ... such as a slug ...

google images show this thing as an armored bug ... what could the ammonia hit .. to irritate it????

ken

Yes, they used to notch my hostas too. Bayer to the rescue.

Ken, it is the root eating larvae that the OP is wanting to get with ammonia. You are right that those heavily armored bugs are almost indestructible...they are so hard shelled, they crunch when you step on them.

-Babka

This post was edited by Babka on Mon, Mar 24, 14 at 14:20

Ahh yes those beetle things!
Over here in the uk they are called vine weevils and I have had plenty of experience with them!
I have to use a product called Provodo which I water on all my summer baskets,camellias and troughs or they would do some serious harm,it's a great product and kills the grubs not the beetle.
I have only ever lost 1 hosta to them and that was a very small one,they don't bother the ones with established roots in my experience.