I discovered borer in my garden. I drenched with Bayer product this spring but got them anyway.
I have newbies just planted the past 2 weeks.Perennial person at local nursery wasnt enthustiastic when I asked her what could be done to protect the new iris. She sold me a Bonide granular systemic product I sprinkled on all irises including the one I dug that was infected.
Her best advise was to drench in the spring. The borers love clay soil which is what we have.

Any more input on this topic would be appreciated. A DG'er said it takes years to eleminate the borer. Guess its an ongoing process.

When you clear borers out of the rhizome soak the rhizome in a bleach solution to prevent any rot. that is the real danger (rot) rather than the borers themselves. Rinse & plant. You have to keep your eye out for the nasty things. Type os soil makes no difference. they hide in the plant & yes it does take several years to get rid of them. check ocer any new plants you receive.

This is one of many short essays on iris borers. Covers the basic problem and controls. Some of the systemic insecticides may not be available in your area. I have not been able to find acephate (Orthene) for several years around here. Merit is available and works well when applied correctly.

http://www.irisgarden.org/bore...

Certainly would prefer nematodes over sprays.

Thanks Jerry - everyone. I will reapply the drench this spring and hope for the best. I drench lilies at the same time.

What can you do if you don't find the borers until August? I've never had borers before, and now they are in nearly every iris I dug up this morning. It was all I could do not to just fling it away from me when I saw the first one squirming in deeper. I am just sick at the destruction they are causing. How do I get rid of these nasty things? I wonder if I got them in the last box of iris I got, because I never had them before. Or maybe they just really thrive in cold, wet springs.

Once they are in the rhizomes, about all you can do is dig every one, inspect, treat, and re-plant. I use" Bayer Long Season Grub Control", it contains" Merit", a systemic insecticide. With systemic type insecticides, you have to be pro-active, and apply them in early spring when growth starts, so they can be "taken-up" by the plant. I THINK the Grub Control is supposed to be good for 3 months( bottles are at the garage, I'll check later), but I re-apply after the last bloom is gone. Nemotodes will work, if you can catch the borers before they get into the plant. Lucy is right about the soft-rot being the big problem. A careful inspection of the leaves, starting in the early spring, and continuing till Aug., will tell you if you have them, and ,if you get them while they are still small, and in the leaves, you can squish them. I've been using the Merit for 5-6 years now, and only occasionally see where a borer has started to work, but they never get very far, before the insecticide gets them. If you grow iris east of the Rocky Mountains, there's gonna' be borers around, so you have to watch those leaves ,close, for signs.....Arlyn

I wonder if Merit would be effective this late in the year? I'll have to go look for the Bayer Grub control. Thanks for your response!

I found borer too.I had drenched in April with Bayer Tree and shrub which containes imideclopr????.
I lost 4 plants and will nolonger plant iris in that area. Bummer.
Maybe Merit is the answer here too.

Many of you deal with problems that would really discourage me. To my knowledge there are no reports west of the Rocky Mountains. In all the years I have raised Iris I am only aware of one and that came in on an ordered rhizomes. Keeping my finger crossed.

The chemical that is in the Bayer products, and has the "trade name" Merit, is Imidacloprid. It needs to be ingested by the grub, or borer, in this case, in order to kill him, and is systemic, which means it's taken up by the plant roots( and to some extent, through the leaves), so when the bug bites the plant, the bud bites the dust! Some don't like chemicals, and use nematodes, but so far, I've had good luck with the Merit....Arlyn

O K Thanks for the spelling support.
I wait for increases to show about 2 inches and drench not only the iris but emerging lilies for the RedLily beetle.
The borer problem is worse than the lily problem.
Imidacloprid is in all Bayer products to one percent or another. 12 month Tree and Shrub grub controle is what I have used.
I dont mind using insecticides either.I dilute according to label.
I use SEVIN mid season for the lily beetle.
There are too many lilies here to pick off and kill every beetle.They dont seem to be as prevenant since the spring drench from the past 4 years.
The iris are a modest number. The SDB's I lost had only just started to put up more than 1 stem.Ahhhh well.

The product I use JoAnn, is a liquid, and comes in one of those "hose end sprayer" bottles. I believe it is meant mostly for grubs in the lawn. I do use the Tree and Shrub ( has some fertilizer ,also)with Merit for control of Emerald ash borer. It's granular, and you sprinkle it on the soil, and water it in. Bayer makes several "controls" containing Merit, and not all are available everywhere, due to different state's regulations. As I said, to me at least, the best thing is a good visual inspection of the leaves, once a week ,or so, starting early in the season. The borer damage is easy to spot, and if you catch him early, still small, and high op on the fan, it's just "squeeze, POP!, no more borer! Arlyn

You have a dark side.

And here I thought I had you fooled! Was it the "squeeze", or the "POP", that gave me away?...Arlyn

Both.Creepy to think of touchoing those nasties

Usually they are "inside" the fan of leaves. You start at the bottom, close to the rhizome, squeeze it between your fingers, and sorta' I slide them up the leaf, you will fell when you get to the worm, and then you'll hear him PoP! It's easy once you get the hang of it, and you don't even touch the worm....Arlyn

A friend who had a really bad problem has had none since he started using the nemotoads. Arlyn, you can't hear the 'pop' when they are small.

Ugh, you guys are making me shudder! Just imagine this little guy doing his shrug a whole lot faster.

These were all down in the rhizome already, so too late to squeeze and pop in the leaves. I guess I'll need to dig and inspect them all. In all my free time. Ha.

Arlyn, next time you get them call me. I want to come squeeze and pop with you.