funny..... :-) I don't know what you could do except dig them up and clean them out, but I totally identify with the squeamishness part... I sometimes think if I ever have to face borers they will win hands down because I'll run the other way faster than they can chew up the whole bed! Yesterday I was out digging up some irises and a bumble bee decided I smelled nice or something and I know I must have looked like a crazy person out there in the yard with my hands flying all over the place slapping myself silly to get the buzzer away from me!

The borers, or the rot which will follow in the wounds, will destroy most of your rhizomes if left alone. Merit is an ingredient in Bayer Tree & Shrub Insect Control, which is still available now. It is a soil drench that could be mixed in a watering can. You could "search" for it here or on google for more details. If you try it, be sure to wear gloves & avoid exposure to it. Otherwise, at least scrape the soil off the rhizomes & shake comet or another chlorine-containing cleanser on them to help dry up the rot. Good luck!

Don't bother with Merit this time of year. The borer larvae are now too large to be affected by it. Merit is only effective on newly hatched borer larvae that are still very tiny. Your only option if you want to treat for borers now is to dig the affected clumps and cut the borers out of the rhizomes, then cut out all rotting rhizome flesh and do a bleach solution soak to try to kill the residual rot bacteria.

Good luck,

Laurie

Perhaps you might try the peroxide treatment. It is supposed to be real effective at stopping root rot and is said to also kill microorganisms in the soil. One ounce of 3% hydrogen peroxide per quart of water. Spray it on the rhizomes as well as the soil surrounding them.

I have a small bed of bearded iris on a slope. They haven't had mulch the past few years, and are not very deeply planted at all. In the past, they have bloomed wonderfully, but the last 2 years there's been nothing. The plants leaf out well, they just don't bloom. I thought they might be overcrowded (anyone with a link to what this looks like?), so I dug some up this weekend. I found several leaves with a little yellow streaking, but otherwise in good shape. However, every single rhizome had either a rotten end or a dried up section. None of the rhizomes were very large, although the plants are normally sized.

Is this borers or something else? Considering the drought we've had for most of a year, it's a wonder the plants are even alive - they don't get any extra watering. The bed drains quickly, so I don't think it could be water rot. However, I didn't see any bite marks or caterpillars, just holes in the dead tubers where I think the root had been. ANy help is appreciated.