Pest Activity -- June 12, 2009
Pest Activity > June12Welcome to the Woody Ornamental Pest Scouting Report for Western Pennsylvania brought to you by Penn State Cooperative Extension. This report is updated weekly with growing degree day counts and insect activity through the end of June. If you would like an email copy of this report, send your request to email@example.com.
As of June 12, the following growing degree days with a base temperature of 50 degrees have accumulated.
Azalea Lace Bug
Black Wine Weevil
Fourlined Plant Bug
Spruce Spider Mites
Emerald ash borer adults are active now. EAB has now been positively identified in Allegheny Township, Westmoreland County. As of June 10, 2009, Westmoreland County was added to the quarantine imposed by the Pennsylvania Department of Agriculture.
Apple scab continues to develop on susceptible crabapples in the Pittsburgh area. This fungal disease is characterized by yellowing leaves that drop prematurely. Resistant cultivars of crabapples include Adams, Callaway, David, Dolgo, Harvest Gold, Indian Summer, Jewelberry, Liset, Profusion, Red Baron, Selkirk and Sentinel.
Fire blight was observed on ornamental pear trees in Oakmont and Gibsonia this week. Blackened, wilted shoots with dead leaves that remain attached are characteristic of fire blight infection.
Hawthorn lace bugs continue to feed on cotoneaster and serviceberry this week.
Mountain ash sawflies were observed feeding on European mountain ash this week.
Oak Leaf Blister continues to develop in the Pittsburgh area. Cool, wet weather in spring favors development of this disease. It is most common on members of the red oak group, including red oak, pin oak, and black oak. Fungicides applications are rarely warranted, and it is too late now to spray for this disease. Fungicides must be applied at bud break.
A mating pair of redheaded ash borers was observed on a dead sugar maple in South Park this week. This native insect attacks newly planted or stressed trees, and does not limit itself to ash trees. Elm, lilac, mulberry, maple, hackberry, oak, sweetgum, linden, honeylocust, crabapples and others are also susceptible. Redheaded ash borers are common pest of cut firewood. Irrigation during dry periods and fertilization to maintain tree vigor can help protect landscape trees from this insect.
Rose black spot continues to develop on susceptible roses due to the frequent rain.
Viburnum leaf beetle damage has been observed on arrowwood viburnums in Oakmont. Yours truly missed seeing the actual larvae, but the damage is typical of the species. They are pupating now, and adults should be active by mid-July. Viburnum leaf beetles overwinter as eggs in the twigs of susceptible viburnums. Prune out egg-containing twigs from October through March before egg hatch to reduce damage from this introduced pest next year.
The next scouting report will be on June 19.