Are there any tall bearded iris cultivars that are resistant to the iris borer? My gardens are infested with it. Cutting back leaves after bloom and good fall cleanup have not been enough.

None . Look into getting nematobes. I am not sure where to get those, but perhaps it can be goggled.

What about an organic spray, maybe Organocide or Safer.

We don't use spray so I have no idea. John checks our plants in the spring & he can usually spot them & squash them n the leaves. We don't have very many, but I was almost robbed of a BB seedling a couple years ago.

I don't know of any Irises that are resistant to borers, CS -- sorry. We don't seem to have that problem here, thank God -- but we sure did when we lived in Chicago!!! I'm really sorry that you're dealing with it -- it's heart-breaking. Seem to remember someone posting about something to spray -- I hope they'll speak up.

The local Iris Society has a page on this. Check it out!

http://www.dvis-ais.org/home.h...

Click the link above. Scroll done to "Iris Culture". There you will see articles on Rot, Fungus, and Borers. Click the appropriate article and enjoy! I use the systemic Bayer granduales and have very little borer issues. I still have them in very small quantities, so it has not been much of an issue lately. If you are against chemicals and/or have a small number of irises you may want to go with the "squish" method.

Misawa77 said:The local Iris Society has a page on this. Check it out!

http://www.dvis-ais.org/home.h...

Click the link above. Scroll done to "Iris Culture". There you will see articles on Rot, Fungus, and Borers. Click the appropriate article and enjoy! I use the systemic Bayer granduales and have very little borer issues. I still have them in very small quantities, so it has not been much of an issue lately. If you are against chemicals and/or have a small number of irises you may want to go with the "squish" method.

Is it too late in the season to use systemic Bayer granduales or would now be effective?

No, it's not too late. I use a "Liquid" product, by Bayer.....Long Season Grub Control......which comes in a 'hose end spray" bottle. The "granular form (at least what we have here....chemical composition of a lot of product vary, from state to state)has an added fertilizer....which I don't want. Either the liquid, or the dry, only lasts about 3 months ( I think it will tell you, for sure, on the label)so I generally make two applications a season. Being "systemic" ,ANY insect that eats ANY part of the plant, will die ! So, DON'T use it on things that the honey bees frequent, and DON'T use it on food crops.....read the label, and follow directions....please !
I recently read of another "green" solution for borers....or so it was claimed....A mixture of Murphy's Oil Soap and water, sprayed on the leaves is "supposed" to help.
As Lucy mentioned, beneficial nematodes work well, but, they can get a bit "pricey'. I think the best "control method" is different for every gardener....how many plants you have, how big a borer problem you have, your personal feelings about chemical use, etc., etc. will dictate which method is right for you. I think most of us use a combination......trying for good bed sanitation, frequent inspection, and "squishing", and either a chemical, or biological control.

Not too late. I put mine down yesterday. It would have been better to do this earlier, but I could not find the time. Lowes has it neighbor!

Trips to four local hardware stores and Home Depot did not turn up any Merit. Might it have been discontinued because of toxicity? I did not go to Lowes, but it is not listed on their website.

Bayer Long Season Grub Control granules is a widely available product here but its application seems to be limited to lawns. So I am hesitant to think that this is what I need. ???

Well it's designed for lawn grubs, but the active ingredient is imidacloprid the chemical that kills the iris borer as well. I use that product in your post above.

tveguy3 said:Well it's designed for lawn grubs, but the active ingredient is imidacloprid the chemical that kills the iris borer as well. I use that product in your post above.

How much do you use per plant, and where do you apply it?

I just sprinkle a small hand full around each iris clump, but not on the rhizomes. (I don't measure when I cook either!) Wear gloves!

I have used the Bayer Season Long granules and also the kind you mix with water. I just put little palm full around the clumps also. I have heard that Merit (same as imidacloprid) only lasts a month so I add more about a month or so later. I use more around irises that are near bushes or evergreens. The moths like to hide and often lay eggs in the evergreens I was told by an iris farmer.

I use the bayer grub control also., I use the spray that attaches to the hose and spray everything when I do. Yard and gardens. When I use the granular form I put it in our grass seed hand spreader and just walk and spin it out.