3 (1 = rare 5 = annual)

4 (1 = very little damage 5 = plants killed)

Bearded iris is most commonly affected; however, it can usually survive attack. Siberian and Louisiana iris are less commonly attacked, but attack normally kills the plants.

Groundcover

• Iris, Crested (Iris cristata)

Perennial

• Bearded Iris (Iris x hybrida)

The main indication that the iris has a borer is the yellow streak caused by a bacterial rot that grows down through the borer's tunnel into the rhizome. Between the borer feeding and the bacterial rot, the iris declines in vigor and appearance (yellowing, browning of foliage). Severe feeding and rotting may kill the iris.

The borer egg hatches and the larva enters the leaf when the leaf is about 4-6 inches high. The insect works its way down the leaf into the rhizome. In the rhizome, the insect continues feeding till it is a full size larvae. The adult moths emerge, mate, and lay eggs on the overwintering plant.

Clean up plant debris before plants begin growing in spring. Use suggested insecticides if necessary when fans are 4 to 6 inches high. Dig up and remove borers, scrape out decay, dip in 10 percent chlorine bleach solution, dry for several hours in sunlight. Replant so that top of rhizome is visible after watering the rhizomes in. Cut leaves to 4-6 inches in height.

Home, Yard & Garden Pest Guide
The Home, Yard & Garden Pest Guide (C1391) provides is written for homeowners and other residents and provides nonchemical and current chemical recommendations for controlling pests associated with trees, shrubs, turf, flowers, groundcovers, vegetables, fruit, and houses. In addition, you'll find detailed information about integrated pest management, pesticide safety, and pesticide application and calibration techniques. This publication may be purchased at your local University of Illinois Extension Unit office, or by calling 800-345-6087, or by placing an order online (search for "C1391").
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Illinois Commercial Landscape and Turfgrass Pest Management Handbook
The Illinois Commercial Landscape and Turfgrass Pest Management Handbook (ICLT) is written for professional applicators and provides nonchemical and current chemical recommendations as well as application timing information for all major pests of turf, woody ornamentals and herbaceous ornamentals. This publication may be purchased at your local University of Illinois Extension Unit office, or by calling 800-345-6087, or by placing an order online (search for "ICLT").
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U of IL - Distance Diagnosis through Digital Imaging
A free plant, weed, insect and disease identification service available through your local University of Illinois Extension office. Center Educators or State Specialists review & respond to information and digital images submitted by local Extension office personnel. Some samples may require further examination or culture work (nominal fee involved) at the U of IL Plant Clinic.
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U of IL - Plant Clinic
Services include plant and insect identification, diagnosis of disease, insect, weed and chemical injury (chemical injury on field crops only), nematode assays, and help with nutrient related problems, as well as recommendations involving these diagnoses. Microscopic examinations, laboratory culturing, virus assays, and nematode assays are some of the techniques used in the clinic.
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