Johnson Ops Tree Care Blog

Hemlock Wooly Adelgid Hemlock woolly adelgid (Adelges tsugae) is a tree-killing insect that was accidentally introduced to eastern North America. It is a threat to Wisconsin’s eastern hemlocks in Wisconsin if it arrives here. Learn where this pest is now, what it looks like, and how to prevent its spread into Wisconsin. A pest of hemlock trees, hemlock woolly adelgid (HWA) is native to the Asian continent. HWA has not yet been found in Wisconsin but has become well-established in several counties in Western Michigan. HWA currently ranges from northern Alabama/Georgia […]

Anthracnose Disease Anthracnose is the name of several common fungal diseases that affect the foliage of woody ornamentals in Wisconsin.  Trees that are most commonly and severely affected by anthracnose include ash, maple, white oak, sycamore, and walnut.  Anthracnose typically affects young leaf tissue. Symptoms vary from host to host, but in general, include irregular spots, and dead areas on leaves that often follow the veins of the leaves.  Affected tissue can vary in color, but is often tan or brown.  Severely affected leaves often curl and may fall off.  […]

Fire Blight Fire blight is the most destructive bacterial disease affecting plants in the rose family, including apple, pear, crabapple, hawthorn, cotoneaster, mountain ash, quince, rose, pyracantha, and spirea.  It can kill or disfigure a tree or shrub, depending on the susceptibility of the host and weather conditions. What does it look like?  Blossoms, leaves, twigs, and branches of plants affected by fire blight can turn dark brown to black, giving the appearance of having been scorched in a fire.  The blighted blossoms and leaves tend to stay on the […]

Chlorosis Chlorosis is a common nutritional disorder of many woody ornamentals in Wisconsin, particularly in the southern and eastern parts of the state.  Pin oaks are most commonly affected by chlorosis, although many other trees and shrubs (e.g., white oak, red maple, white pine, and Rhododendron spp.) are also very susceptible. What does it look like?  Symptoms of chlorosis are easy to distinguish from those of other diseases.  Affected leaves turn yellow, except for the veins, which remain green.  In severe cases, foliage may turn brown and die.  Symptoms can […]

A Simple Guide To Wasp Nests In Trees Maintaining the upkeep of healthy and functional plant life requires knowledge of the ins and outs of the insects that can build a home on your trees. Wasps often live in your gardens and can be seen among the tree branches. Knowing more about a wasp’s behavior can help you keep safe in your garden. For any homeowner who owns a garden with trees, keeping on top of the ecosystem is vital. When a nest is spotted, people will rush to call […]