Plant Information

Plant Information

Pests and Problems

<p>Pests and Problems</p>

Boxwood Blight

The University of Illinois Extension Program has created a fact sheet for identification of boxwood blight. Download the fact sheet here.

Giant Hogweed

Questions regarding ID of giant hogweed (Heracleum mantegazzianum) are not common in our region. This plant is not found at the Garden, and homeowners looking to identify the species and the threat of several related plants can find information and side-by-side photo comparisons on this newsletter from the University of Illinois Extension program:

Wild Parsnip

This poisonous weed is most commonly found in roadside ditches and prairie areas—not in cultivated yards and gardens. Looking similar to Golden Alexander (Zizia aurea) or a yellow version of Queen Anne's lace (Daucus carota), wild parsnip blooms later in the season, has deeply forked leaves, and has more leaflets in each compound leaf. Chemicals in the sap of the parsnip react with sunlight and cause phytophotodermatitis—a breakdown of cells and tissues when the sap on the skin is exposed to sunlight.

Gypsy Moths

Susceptible Plants
More than 300 species of trees and shrubs, particularly oak (Quercus), apple (Malus), linden (Tilia), birch (Betula), hawthorn (Crataegus), aspen (Populus) and alder (Alnus)

Emerald Ash Borer

Recommended alternatives to replace damaged ash trees can be found in Ash Tree Alternatives.


Periodical Cicada (17-year)

Periodical Cicada
The periodical cicada (Magicicada), is a native North American insect species inhabiting the eastern United States and, according to Penn State University, is found nowhere else in the world.

White-tailed Deer

Susceptible Plants
Although some plants are more deer-resistant than others, deer will eat almost any plant if they are hungry enough, especially during winters with large amounts of snowfall and high populations of deer.


Susceptible Plants
Broadleaved evergreens (boxwood, rhododendron, azalea, holly, etc.) and needled evergreens (yew, arborvitae, spruce, pine, etc.)

Description & Symptoms
Winterburn is a cultural condition that affects plants that do not lose their leaves over the winter. Leaves turn yellow and then brown in response to specific weather conditions. Leaves do not actually burn but rather dry up.

Black Vine Weevil

Susceptible Plants
Conifers, especially yew (Taxus); broad-leaved evergreens, especially rhododendron, azalea (Rhododendron), euonymus, and English ivy (Hedera); deciduous plants, including climbing hydrangea; and greenhouse plants including impatiens, cyclamen and gloxinia (Sinningia).

Fall Webworm

Susceptible Plants
Most deciduous trees

Description & Symptoms
Fall webworms form large, prominent whitish-gray webs at the ends of branches of deciduous trees. The location of the webs on the outer canopy distinguishes the fall webworm from the eastern tent caterpillar, which nests in webs in the crotches of trees.