Every morning I walk around my garden checking out everything and yesterday I saw where my Boysenberry Buttercup had rotted and it looked fine the day before. I dug it up and there were six yes six borers in the rhizome, talk about being sick, now I'm worried about all the other rhizomes in that bed.

Uh-Oh Vi -- you need to treat the whole bed!!! I'm so sorry..................

I am sorry Vi. I love finding good surprises in my garden and really, really hate finding the bad ones. It does seem like things can go seriously wrong overnight. How are you going to monitor the rest of the irises in that bed?

Tell me how to treat the whole bed MaryAnn.

Well -- when we found a borer infestation (many years ago in Chicago) -- we dug up every Iris and soaked them in bleach water. Then we pared away any damaged flesh of the rhizome -- and replanted them. If I were doing it now, I would sprinkle Comet cleanser on the raw rhizome tissue before replanting.

There may be an easier way to do this -- if so, I hope someone else speaks up. How many Irises are in that bed?

@crowrita1
@tveguy3
@DaveinPA

Darn, I hate to hear that !! It's unusual to find more than one borer in a rhizome...but even one is too many ! I would say that any insecticides you use would have to be "systemic', and then they are only effective while the borer is actually "eating". As MaryAnn said, depending on the size of the bed, a very close inspection of each plant, 'manually" killing / removing the borer, and treating for rot may be your only choice. Good Luck..........Arlyn

Vi, Sorry to hear about your borer problem. I had that happen about 4 years ago. I got a product made by Bayer called "Bayer Advanced" It will kill them all within 24 hours. I spread it around the bed and watered it in. The active ingredient in it is Trichlorfon. Then in the spring you should uses another product, a systemic also made by Bayer. It's called Grub Control, and the active ingredient in that is imidacloprid. I didn't dig up everything and replant, as they were well established clumps. I didn't loose any, but some were set back a while. If there are products made by other companies, just make sure they have the same active ingredient. Good luck!

Oh Vi. I am so sorry. Hopefully Tom's suggestion will work well for you!

Vi.. I would think it would be to late in the year for them to be still in the bulb but once again I have not had much experience with them up until this year, I have never seen them in my garden until this year but then again what a weird year for plants in Iowa there has been a lot of 1st's in 2014 for me at this time of the year at least here they are supposed to be in the moth stage and laying eggs for next year

I would be surprised if they were active that far south have heard of them in Tennessee but Mississippi is a stretch. I have found grubs or worms in my bulbs with rot they are not borers all though they look like them.. Borers have a distinctive look with a pink/red head so would guess that is not what you are seeing and Borers will eat each other from what I understand it is rare to find multiple alive once they reach the bulb. If you can take a picture of what you are looking at.

Iris borers are cannibalistic, you may get a bunch in fans when they are smaller, but by the time they get to the rhizome, there is only one left. Do you have pictures of the critters?

Vi,
Be sure they are truly iris borers. As stated by Brad it would be unusual for them to be that far south. Here are some pix to compare:




There are lots of other critters that will take advantage of rhizome damage. Borers are usually detectable by some leaf damage and some "frass" [droppings] around the fan base.

Vi I am so sorry to hear that! I have no experience dealing with borers.

Comanche Acres Iris Garden sells a spray for iris borers: http://www.comancheacresiris.c...

If you prefer to try a non-chemical solution here is some information on Nematodes from a page (from University of Minnesota) on iris borers:

"Beneficial nematodes are a natural option to help control some boring insects. These nematodes are microscopic worms that seek out and kill the caterpillars by introducing a bacteria. Research results using nematodes have been inconsistent, although they can potentially be effective in reducing iris borer populations.

Two species of nematodes are commercially available from natural garden supply catalogs or your local garden center. Both species (Heterorhabditis and Steinernema) have been shown to attack iris borer. Nematodes need a moist environment to survive and move. The easiest time to apply is during a rain shower. Lacking rain, water iris before and after applying nematodes. Apply nematodes when iris leaves are almost fully expanded but before flowering. Repeat the treatment approximately one week later. Nematodes are perishable; check the label for the expiration date."

Source: http://www.extension.umn.edu/g...

Here is the American Iris Society page on Pests and Diseases of Irises, it has a section on borers: http://www.irises.org/About_Ir...

And finally a page from the Missouri Botanical Gardens on iris borers: http://www.missouribotanicalga...

When you get things back under control...or next spring if the timing is better I can sent you a rhizome of Boysenberry Buttercup.

Good Luck!

Surprised to find that many borers. They are cannibals. They may be clustered on the one plant. check the leaves of the other plants, the ones with borers have sticky substance near the edge of the leaves.

Those look like what I found on one ear of corn. Are corn and iris borers similar or the same?

Different critter!

Hi I was gone most of yesterday. I want to thank everyone for responding to my problem.

Dave, your pictures look like my borers but mine were orange in color, I wish I had taken a photo but all I wanted to do was squash them into the concrete, so now I am not sure what I had or what I should do.

I dug all between the Iris in that bed looking for more but did not see any, I have about 18 Iris in that one bed and as of this morning they are all looking healthy but I am going to keep checking and if I find another I will take a photo.

I'm thinking maybe I should do what Tom said and use that Bayer Advance in that bed.

Marilyn, thanks for all that info you sent and also for the offer of a new rhizome, maybe I will take you up on that come spring.

I will keep you all updated on what is happening and once again thanks to all you guys for your help.

Vi - The iris borers would not be in the bed in the form you are looking for. They start out very small in the mid-fan height area and chew their way down towards the rhizome. They eat other borers on the way down getting as big as your photos. They then go into a cocoon of sorts which would be in the soil until they hatch as moths.

Finding them now in the stage you did is surprising to me. This puts you about three months behind a "normal" iris borer schedule. This and having multiple borers in the same rhizome is unusual at best.

I have a hunch that the rhizome was rotting for some reason, and some other kind of grub has found that to munch on. I'd still use the grub killer on the bed, you don't want them around what ever they are.

At this time of year you would find the brown pupae of borers, not the borers themselves. I agree with tom about another insect eating the rot, not causing it.