No. 13/July 31, 2009
Japanese beetles, white grubs, Zimmerman pine moths, fall webworm, walnut caterpillar, whitemarked tussock moth, and other late summer caterpillars are discussed.
Magnolia scale is common this year in northern Illinois. We have received numerous requests for information, so this article is being provided to help answer client questions even though it is still too early to achieve effective control.
Lantania scale, Hemiberlesia lataniae, occurs on a wide range of plants and is more common in the southern U.S. where it feeds heaviest on Australian pine (Casuarina), loquat, rose, and various palms.
Rhododendron Root Rot
Two major hurdles to growing healthy rhododendrons in Illinois are clay soil and high pH levels of the soil. Rhododendrons thrive in acidic, well-drained soil. To make matters worse, Phytophthora root rot is a common disease on rhododendrons in wet sites.
Dutch Elm Disease or Elm Yellows
There are still many elms in Illinois and many of those are American elms. Each year at the Plant Clinic we culture elm samples for the presence of the Dutch elm disease (DED) fungus.
Clematis is host to a fungal leaf spot called Ascochyta leaf spot. The cause is a fungus, formerly called Ascochyta clematidina, but now known as Phoma clematidina.
Invasive Species Spotlight: Viburnum Leaf Beetle
Last week, the Viburnum Leaf Beetle was confirmed in Illinois for the first time. A few beetles were positively identified on a viburnum planting in Cook County. This invasive beetle is native to Europe and is currently found in New York, Maine, Massachusetts, Pennsylvania, and Ohio.