No. 16/September 10, 2012

Borer Increase Likely After Drought
Insect borers are likely to be more numerous than normal for the next several years. During extended dry conditions, trees lose root mass, resulting in a reduction of sap flow and dieback of branches. The reduced sap flow provides opportunities for borer attack that would not be present otherwise. This increase is likely to be noticeable next year and will build for about three years. Borer infestations are likely to fall over the following two years until reaching normal levels around 2018.

Scale Increase Due to Drought
There are a couple of scale species that become much more numerous after droughts and other tree-weakening events. European fruit lecanium scale becomes very common on stressed trees and remains in high numbers for several years until the tree recovers. It is common on maples, oaks, hazlenuts, crabapples, and many other tree species. Large infestations produce high amounts of honeydew such that it feels like it's raining under the tree.

Phytophthora on Rhododendron, but on the Leaves, not the Roots
A rhododendron sample was recently submitted to the U of I Plant Clinic by an Illinois Master Gardener. She suspected that her rhododendrons, just recently purchased from a nursery, were infected with Phytophthora. We normally think of Phytophthora as a root rot pathogen, but in this instance, the foliage was infected. The symptomatic leaf tissue was first tested for the presence of Phytophthora sp. by using an Agdia ELISA quick strip test at the U of I Plant Clinic. The sample tested positive for the presence of Phytophthora.

Fairy Rings on Turf
Heavy rains over the past week have promoted the growth of mushrooms in landscapes across Illinois. On turf, mushrooms can form in distinct circles or arcs, a condition referred to as "fairy rings." Fairy rings obtained their name from old folklore that theorized the rings to be areas where elves, pixies, or fairies danced and played.