No. 8/June 23, 2014

Guignardia Leaf Blotch
Guignardia leaf blotch is a fungal disease that affects many Aesculus species. In Illinois, this disease is commonly seen on the common horsechestnut (Aesculus hippocastanum). Symptoms begin as rapidly enlarging, irregularly shaped, water-soaked areas.

Modified Growing Degree Days (Base 50°F, March 1 through May 15)
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 in this article along with the degree day accumulations to determine what insect pests could be active in their area.

Illinois Invasive Plant Phenology Report
Several invasive plant experts from around the state have started a new series of reports focusing on the phenology of invasive plants in Illinois. The intent of these reports is to provide an update on the development of invasive plants across the state of Illinois -- what plants are in bloom, leafing out, setting seed, or senescing in different areas of the state.

Thousand Cankers Disease Confirmed in Indiana, Fungus Found on Insect Other than Walnut Twig Beetle
The Indiana Department of Natural Resource issued a press release on Friday, June 20 announcing the detection of Thousand Cankers Disease in Indiana. Indiana joins Maryland, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, and eight western states with the disease.

Palmer Amaranth -- A New Weed to Watch For
Ask any cotton farmer what has been their biggest weed problem of recent years and they will all likely tell you the same: Palmer amaranth (Amaranthus palmeri). This plant has put some southern farmers out of business. Midwest farmers are now or will soon be well acquainted with this fast growing and yield robbing species as it is moving northward across the Midwest.

Japanese Beetle
Japanese beetle adults are present throughout Illinois. Robert Bellm, Extension Educator, reported their presence in Madison County, and Ed Nangle, Chicago District Golf Association, reported their presence in Cook County. Last week in this newsletter, we predicted low numbers in the northern half of the state due to the extended deep soil freezing last winter.

Fall Webworm
Fall webworm is named for infestations that occur in the northern part of the United States only in late summer to early fall. In the southern half of the United States, including the southern half of Illinois, fall webworm has an additional generation in early summer. This first generation of fall webworm is now feeding in southern Illinois.