No. 2/May 8, 2017

Hello, Weeds of Yellow!
Yellow flowers are eye-catching. The descriptions of a few that have been garnering attention this spring follow, including butterweed, fig buttercup, and yellow hawkweed.

Gymnosporangium Rusts on Eastern Red Cedar
Gymnosporangium rusts have been active in many parts of the state for a few weeks. Three Gymnosporangium rusts commonly affect trees in Illinois landscapes: Cedar-apple rust, Cedar-hawthorn rust, and Cedar-quince rust. As their name suggests, these pathogens require two hosts to complete their life cycles. A portion of each disease's life cycle occurs on Juniper hosts, while the remainder occurs on one of several deciduous host within the Rosacea family.

Modified Growing Degree Days (Base 50°F, March 1 through May 4)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.

Brown Marmorated Stink Bug Information for Homeowners
The brown marmorated stink bug (BMSB) should be old news for Illinois residents by now. What may be new to some though, is its increased numbers in their homes. While it is quickly becoming the time of year where these insects are found outdoors, many people reported seeing this pest for the first time in their homes last winter.

Viburnum Leaf Beetle Activity Observed in Northern Illinois
Another invasive pest that is gaining notoriety in Illinois is the viburnum leaf beetle. This defoliating insect has been reported for several years in northeastern Illinois; in recent years reports of damage have become more widespread in that area. Our first reports of larval activity has been reported in Cook and DuPage counties over the last week and a half.

Chipmunk vs. Ground Squirrel
Two little furry creatures run around yards, potentially wreaking havoc on plants and the soil: the Eastern chipmunk and the thirteen-lined ground squirrel. They can be easily confused and are often treated as one.

Insect Degree Days and Phenology Update
An article in the previous issue of this newsletter two weeks ago indicated that insects were approximately one week ahead in northern Illinois, and two weeks ahead of a normal spring in central and southern Illinois. Due to the cooler weather of the past two weeks, one can see from Kelly Estes' article in this issue on degree days that we are approximately two days ahead of normal on insect development in northern Illinois, four days ahead in central Illinois, but still about ten days ahead in southern Illinois.

Pest Watch
Pests such as viburnum leaf beetle, European pine sawfly, spruce spidermite, arborvitae mite, juniper mite, and pine mite are discussed.