Ugh, how do I get rid of borers?

I just went out to divide some iris, thinking maybe that was why they've done so poorly this year, and discovered I have borers, for the first time ever. I wondered why so many were fizzling out and disappearing, but just hadn't had time to really investigate. How do I get rid of these disgusting things? I have tons of iris spread throughout all of my beds, not all in one central location, so this is going to be a major endeavor. Also, whatever I use MUST be bee friendly. I have a very healthy, busy bee population in my yard, and I don't want to do anything to endanger it!

Well, I keep bees, and I use chemical borer control and have never seen a problem, but it's too late for insecticide, at this stage anyway. So, unless someone else has a system, all I can recommend is dig, inspect, kill the borer (s), treat for rot( 10% bleach dip, and Comet cleanser), and replant. Benificial nematodes can be effective for borer control, but ,again, it's too late once the borer is in the rhizome. If you search for articles here, and on the other iris forums, you'll find lots of info, and a"google" of iris borer control will get you tons more. Good Luck...Arlyn

Thanks, Arlyn. I appreciate the quick response!

Bookerc1 -- I learned quite a bit about iris borer prevention and control on this forum a few years back. Fortunately I had printed out those documents, thus making it easier for me to locate them electronically. Below are links. There is a very informative article by Jill Nicolaus as well as a couple of helpful threads. As you go through the threads, concentrate on those posts by DG user: laurief.

Basically, each early spring I remove ALL over-wintered foliage from my bearded irises. Then I apply GrubEx, using a half teaspoon to a whole teaspoon to each clump depending on the clump size, then I water in (unless rain is in the forecast. Actually good garden hygiene is the best defense. Getting rid of those old leaves is critical. If there are borer eggs at all, that's where they will be. The important thing, if using GrubEx (or comparable product with imidacloprid as the active ingredient), do so BEFORE you have 2 consecutive days of 70+ degrees.

I might add that I have lots of bees in my garden. The use of GrubEx seems to have no adverse ecological effect in my own garden.


http://davesgarden.com/guides/articles/view/123/
http://davesgarden.com/community/forums/t/791601/?hl=fall+cut+back+on+iris
http://davesgarden.com/community/forums/t/583164/?hl=IRIS+BORERS

Good luck!

Thanks, figaro52. I am so cautious about using any pesticides, but I've put so much money and work into my iris, and I've lost so many this year! Is it a particularly bad year for borers? I've never had them before, and I've dug and shared many iris this time of year in the past, without ever encountering a single one.

This is really the only time I use chemicals. Just getting rid of all over-wintered foliage in early spring may be all that's needed to prevent borers.