No. 7/June 5, 2009
We have had several cases of boxwood leafminer, Monarthropalpus buxi, sent in to the plant clinic this spring. Boxwood leafminer causes off-green pouches on leaves that turn brownish as the larvae mature.
We are also seeing some damage caused by boxwood spidermite, Eurytetracnychus buxi. Initial damage appears as light green squiggles across the leaf upperside.
Pearleaf Blister Mite
Extensive damage from pearleaf blister mites, Phytoptus pyri, has been reported on ornamental pears. This is an eriophyid mite that attacks not only apple and pear fruit and ornamental trees, but also other rose family trees including serviceberry, cotoneaster, hawthorn, and mountain ash.
Reports from the Illinois Department of Public Health show that disease incidence from ticks has been rising over the last few years. Although the number of reported cases is a small percentage of the population, it is still important to protect yourself from these giant mites.
Rotting Iris Plants
If you are seeing rotted iris plants, chances are the plants have bacterial soft rot. This bacterium, Erwinia carotovora is present in most soils and will invade through wounds.
Juniper Tip Blight
If you are seeing discolored new growth on your junipers, it is likely that Phomopsis tip blight is to blame. Sprays to control this disease are made beginning when new flushes of growth appear.
Invasive Species Spotlight--Hydrilla
Hydrilla is an aggressive invasive plant that can rapidly displace native aquatic vegetation. These non-native plants form thick mats under water that shade out native vegetation, block the flow of water, and impede fishing and recreational activities, among other things.