Clinic Update: Late Spring Samples Submitted to the Plant Diagnostic Clinic

Cedar Apple Rust. Photo by Simeon Wright.

We have had a lot of spring weather fluctuations in Missouri which has resulted in a variety of sample submissions in the clinic. What follows is a description of what we have received in the past several weeks.

Many of our samples continue to be from trees. Most of these samples continue to be weather-related injuries associated with drought and winter temperature fluctuations, although we have also received samples with diseases that relate to periods of cooler, wet weather this spring and the usual herbicide drift issues. It is important to remember that it is difficult to diagnose from completely dead, dried out branches, whether it’s a suspect disease or herbicide injury issue. Our diagnosis is only going to be as good as the sample we receive, and a poor sample is a waste of time and money to submit. When possible, select branches that show symptoms but have not completely died. In some cases, it is helpful to submit root material as well. For suspect vascular wilts such as Verticillium, Dutch elm disease and oak wilt, it is important to select live branches displaying symptoms 1-2 inches in diameter cut from areas of the tree that are beginning to show symptoms and to include the leaves. Keep the sample cool and fresh and submit as soon as possible after collection. You can contact the clinic for instructions on what to submit for various types of problems.

Some specific disease, insect and other tree problems the clinic has diagnosed recently include anthracnose on oak, pecan and sycamore. From fruit trees, likely cases of fire blight on apple and pear, as well as cedar apple rust. We have one confirmed case of Dutch elm disease on an elm, hickory samples with Phylloxera galls, pin oak with iron chlorosis, poplar and red oak with thrips damage, lilac with powdery mildew and maple with maple bladder gall.

Rhizoctonia on impatiens. Photo by Simeon Wright.

We have also received several vegetable and ornamental samples. In addition to a number of herbicide drift issues, we have received a number of disease-related samples and a few nutritional and insect problems. From tomatoes, we have received samples with physiological leaf curl, as well as a number of probable growth regulator herbicide drift issues, virus issues, Septoria leaf spot and bacterial leaf spot. From watermelon, we have had a confirmed case of Fusarium wilt. Ornamental samples included impatiens with Rhizoctonia stem rot, rose with rose rosette disease, snapdragon with Pythium stem and root rot, pachysandra with Volutella blight and zoysia with large brown patch.

We look forward to receiving your samples. Not only does an accurate diagnosis allow you to manage your plant problems, your samples also allow us to see what’s happening around the state. Please refer to the sample submission section of our Website http://soilplantlab.missouri.edu/plant/index.htm or contact us for more information on sample submission.

Simeon Wright
573-882-3019