I wanted to ask a question about the bearded iris rhizome pest, but the topic is not. A question ripe in connection with the order of chemical protection products for our plants. . Question: On the bearded butterscotch root, starting from mid-May, you can see the moves, I would say the wireworm has tried, and it is in the root zone. What can it be, and how can we get rid of it?

Kilerobbins!

Where are you located? In America we have iris borer (Macronoctua onusta) that feeds within the leaves in May and later moves to the rhizome (July-August).

Cleaning up dead leaves and stalks in late autumn and in spring helps get rid of the eggs.

Some people apply a systemic insecticide to the soil in spring (imidacloprid).

Do you have pictures of the pest?

Imidacloprid is banned in Maryland and not able to be legally shipped here, either. Be aware it could poison your ground water, and render the soil unsafe for subsequently growing fruits and vegetables.

Thanks, Daisy. I don't use imidacloprid on my irises because I know it is systemic, which means it can be carried into the blooms and therefore may affect pollinators, so I've wondered why it would be labelled for control of iris borer. I just made a quick look at various imidacloprid labels and have been unable to find iris borer listed. I know others on the forum use it: anyone want to comment? Is there a specific imidacloprid product labelled for iris borer?

I think somewhere I read that the new iris cultivars are hard for insects to pollinate, so maybe there is less concern in that regard.

I have always used Bayer 2 in 1 Rose and Flower on my irises in early spring. Last year they changed the formula from imidacloprid to acephate which does not curtail the borers. You have to check the label to make sure. If you are very observant, you can spot the telltale signs of the borer travel and smash them in between the fans before they get to the rhizome. Fertilome has a tree and shrub drench that is effective in killing the borers but is also systemic. I still have lots of bees on my other plants so do not think the irises are their primary source of pollen or if so, they are still buzzing around every year.
Some folks use some sort of nematodes but I am not as familiar with that process. Borers can devastate an iris bed if allowed to go unchecked.