No. 4/May 14, 2012

Weather & Insect Emergence
The weather over the last week was close to normal for this time of year, except that northern Illinois was slightly cooler.

Emerald Ash Borer
Emerald ash borer was found in three new counties from last fall into this spring. These include rural Farmer City in DeWitt County in September, in Fairbury and at the rest area near Pontiac in Livingston County in February, and in northern Decatur in Macon County in April. The Decatur location is near rail lines. Emerald ash borer adults have emerged throughout the state.

Hydrangea Leaftier
Hydrangea leaftier, Olethreutes ferriferana, has been noticeable in northeastern Illinois and is present in other areas of the state. Damage appears as three or four cupped leaves tied together with silk at the end of a branch at the top of the plant. An attacked plant will typically have ten to twenty of these cupped leaf sets. Pulling the leaves apart reveals a slender greenish caterpillar up to one-half inch long with a blackish head.

Hemlock Woolly Adelgid Found in Nearby State
The Indiana Department of Natural Resources recently announced that the hemlock woolly Adelgid was identified in the state for the first time. This invasive insect was found on a landscape tree in LaPorte County in mid-April.

Anthracnose on Sycamore makes them appear as "Sick-a-more"
Many sycamores are infected with anthracnose in Illinois every spring; however, the intensity and duration of infection is dependent on the weather. Most Anthracnose diseases thrive during cool and wet conditions. In addition, dry winters may stress trees, which can make trees more susceptible to disease.

Bacterial Blight of Callery Pear
This spring, many Callery pears in Illinois are showing symptoms of Bacterial blight, a disease caused by Pseudomonas syringe. This is a weak pathogen known to infect many species of ornamentals, especially when the plants are under stress. Like many bacterial pathogens, it requires a wound or natural opening to enter the plant.