Issue no. 3 of the Home, Yard & Garden Newsletter is now available
IN THIS ISSUE:
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Bridalwreath Spirea and Insect Management
Bridal wreath spirea, or Vanhoutte spirea (Spiraea x
vanhouttei), is blooming in throughout the state. This is a major phenology
plant in Don Orton's book Coincide. With phenology, stages of plant development
(usually bloom time) are used to predict stages in pest development. This
method is more accurate than using calendar dates because the plant is exposed
to the same climatic conditions as the insect.
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Hydrangea Leaftier
Hydrangea leaftier, Olethreutes ferriferana, has been
noticeable in central Illinois and is present in other areas of the state.
Damage appears as two to four cupped leaves tied together with silk at the end
of a branch. An attacked plant will typically have ten to twenty of these
cupped leaf sets. Pulling the leaves apart reveals a slender greenish
caterpillar up to one-half inch long with a blackish head.
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Euonymus Caterpillar
Euonymus caterpillars are numerous in northeastern
Illinois. This insect rarely occurs in Illinois south of Kankakee or west of
Rockford. Its main host in Illinois is European euonymus, Euonymus europaea. It
is listed as also attacking spreading euonymus, E. kiautschovicus, and winged
euonymus, E. alatus; but I have not received reports of it feeding on those
hosts. European euonymus is a slender, large shrub to small tree.
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Azalea Sawfly
There are three sawfly species that commonly attack
azaleas, two in the spring and one in the summer. We are apparently currently
seeing Amauronematus azaleae. There is one generation per year with the adults
emerging to lay eggs on expanding leaves in the spring. The larvae are feeding
at this time in central Illinois and apparently prefer mollis hybrid azaleas,
which are deciduous. Nearby evergreen azaleas are not attacked.
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Dealing with Tree Seedlings in the Lawn and Landscape
The maples are currently on a mission to reforest the
Earth. The ash, cherry, and mulberry trees are often on the same
mission. What can you do?
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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 below with the degree day accumulations above
to determine what insect pests could be active in their area.
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Emerald Ash Borer Emergence Approaching
Historically, as we approach the Memorial Day weekend, we
begin to be aware of the possibility of emerald ash borer (EAB)
emergence. Emerald ash borer emergence is predicted to begin when the
accumulation of degree days reach 450—500. Several areas of the state have
reached or are closing in on that threshold.
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Illinois Invasive Plant Phenology Report
Several invasive plant experts from around the state have
started a new series or 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.
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Impatiens Downy Mildew
Impatiens Downy Mildew (IDM) continues to threaten one of
the most popular shade-tolerant bedding plants used in American landscapes. At
one point, impatiens was the number one bedding plant sold in the United
States. However, as a result of IDM, many growers have opted to cut back on the
number of impatiens grown or avoid them all together.
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Basil Downy Mildew in 2014
A sample of basil from Wisconsin was diagnosed with downy
mildew last week at the University of Illinois Plant Clinic. Basil downy mildew
was a serious problem last year and, depending on the weather, we may be seeing
more of it in 2014. This pathogen affects both homeowners growing a few basil
plants for fresh harvest, and the producers who cultivate commercial basil in
Illinois.
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