Issue no. 3 of the Home, Yard & Garden Newsletter is now available

IN THIS ISSUE:

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Bridalwreath Spirea and Insect Management

http://hyg.ipm.illinois.edu/article.php?id=569

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

http://hyg.ipm.illinois.edu/article.php?id=570

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

http://hyg.ipm.illinois.edu/article.php?id=571

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

http://hyg.ipm.illinois.edu/article.php?id=572

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

http://hyg.ipm.illinois.edu/article.php?id=573

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)

http://hyg.ipm.illinois.edu/article.php?id=574

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

http://hyg.ipm.illinois.edu/article.php?id=575

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

http://hyg.ipm.illinois.edu/article.php?id=576

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

http://hyg.ipm.illinois.edu/article.php?id=577

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

http://hyg.ipm.illinois.edu/article.php?id=578

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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May 10 Issue of the Morton Arboretum Plant Health Care Report

This issue contains information on:

European pine sawfly
boxwood psyllids
carpenter bees
downy mildew on impatiens
Volutella on pachysandra
creeping bellflower

Issue no. 15 of the Home, Yard & Garden Newsletter is now available

IN THIS ISSUE:

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West Nile Virus

The hot, dry summer has apparently been responsible for higher levels of West Nile virus earlier this year in Illinois. The virus is reaching levels about a month earlier than is typical. As it normally builds from mid-August through the fall, this early increase followed by human cases makes it likely that its impact will be much higher than recent years. This increased level makes it important to protect landscape workers and others involved in outdoor activities.

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European Paper Wasp

European paper wasp, Polistes diminula, has been identified in Urbana in central Illinois. This wasp has been in northern Illinois for several years. In North America, it is found in southern Canada and the northern U.S., being common in Ontario, Michigan, Ohio, and Wisconsin. It has not been found south of southern Virginia. In the eastern hemisphere, it is native to southern Europe and Asia and northern Africa. It will surely continue to spread farther south in the U.S.

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Downy Mildew of Impatiens Is Back in 2012

This week, the U of I Plant Clinic has confirmed downy mildew of impatiens (Impatiens walleriana) in Cook County.  It is apparent that the recent rains and cooler night temperatures provided the perfect environment for disease infection.  Earlier this year, in HYG issue #3 I warned readers to watch out for this unbelievably destructive disease.

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Bleeding Canker on European Beech

Bleeding Canker is a potentially lethal disease to mature European Beech trees (Fagus sylvatica). Researchers at Cornell University have been working extensively with this disease and have identified three closely related species of Phytophthora that are involved. Phytophthora plurivora, P. pini and P. citricola all cause similar bleeding canker symptoms.

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