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Integrated Pest Management

iris borers

16 years ago

I have never seen one, but I believe that my iris are infected with iris borers.The iris have brown spots on the leaves, and some rhizomes are rotten; there are places on the leaves which show the outline of some kind of caterpillar.

I googled iris borers and found the Bayer site, which has a grub control for lawns. This grub control has the chemical in it that I need to kill the iris borers. Does anyone know if that is what is messing up my iris, from what I have said?

If so, do I use the Bayer stuff? I cannot bear to kill these plants--they are my favorites. They are planted on a site that is well-drained, with clayey type soil; in full sun.

Any help you can give me would be much appreciated! BBBunn

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Comment (1)

Kimmsr
16 years ago
If you had Iris borers you would find the grub in the rhizome around the soft, "rotten" parts. If you have them the best time for control is shortly after you see the signs of the larva tunneling down the leaves into the rhizome. Dig them up, cut off the soft, eaten, areas of the rhizome, feed the wee buggers to the birds. Dusting the soil and leaves with a pyrethrine based dust may help some, depending on where the larva come from. Many people wil tell you to clean up all debris in and around the bed to eliminate potential overwintering sites for the parent, but that also eliminates hiding places for any potential beneficial insects that could aid in control.
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