No. 1/April 29, 2019

First Issue 2019
Welcome to the 2019 edition of the Home, Yard, and Garden Pest Newsletter. This newsletter is written to keep professional landscapers, arborists, golf course superintendents, lawn care personnel, and garden center operators up-to-date on the commercial management of diseases, weeds, insects, and other pests. We will report on the pests we are seeing and anticipating throughout Illinois. To assist us in these efforts, we ask for your help in reporting pest situations as you see them throughout the year. Please send reports to the newsletter coordinator, Travis Cleveland, at

Pest Management in the Garden
Warm weather has arrived and our plants are starting to green-up and bloom. That also means weeds, insects, and diseases are starting to become active too. As the saying goes, the only things guaranteed in life are death and taxes, and if you’re a gardener you can also include pests in the list of life’s guarantees.

Hawthorn leafminer
Hawthorn leafminer (Profenusa canadensis) are small sawfly larvae that feed between the epidermal layers of the leaf, on the parenchyma cells, leaving small discolored tunnels behind them. The areas on the leaf where tunneling has occurred eventually become brown patches. The adults are small black sawflies about 3 mm long. One of the major characteristics used to differentiate sawfly adults from other wasps can be seen when you examine the body where the thorax and abdomen meet. Many wasps have a slender “waist” that connects the thorax and abdomen, but sawflies lack this slender waist and it can be difficult to see where the thorax ends and the abdomen begins.

Brown Boxwoods
Each spring we receive questions regarding browning boxwoods. Boxwoods are broadleaved evergreens that are prone to winter injury. This year’s prolonged winter was especially harsh on many boxwood cultivars, particularly those in the Northern portion of the state. I’ve both observed and received reports of entire plantings with leaves that turned tan or brown. Extreme cold temperatures and winter desiccation likely contributed to this injury. At this point, nothing can be done to save the injured leaves. However, given time and patience, new leaves will emerge, and the shrubs will likely recover. You can also check the extent of the injury lightly scratching a stem. If you see green tissues, that is a good sign that the branch survived. If you see brown tissues, the branch is likely dead. Once you are confident of the extent of the injury, you can carefully prune out the affected shoots.

Mowing the Lawn
When it comes to lawn care, mowing is a fundamental aspect of lawn maintenance. If done incorrectly, the cut will result in a thin, weak, weed infested lawn that will continue to be a problem that cannot be corrected by mowing alone. However, if properly mowed, the lawn will be uniform, dense and attractive. There are four elements to mowing that should be considered: cutting heights, mowing frequency, mowing pattern, and disposal of clippings.

Glyphosate and Risk Communication
Currently, there is much perceived risk associated with using glyphosate. It is all over the news and in the papers. We are receiving more questions and calls on this topic, and from what you have told us, you are too. Clients are concerned. Applicators are concerned. Recently a second jury found that glyphosate was responsible for causing the plaintiff's cancer. Many experts disagree with these verdicts. It’s important to keep in mind that these court decisions do NOT change the current body of science. Unfortunately, juries are not necessarily making decisions based on science as unavoidable human emotions come into play. The International Agency for Research on Cancer (IARC) determination of “probable human carcinogen” identified glyphosate as a potential hazard. Many governments, including USEPA, have published risk assessments about glyphosate, finding it is unlikely to cause cancer in humans when used according to the label directions as required. Still, questions abound.