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James A. Chatfield, Ohio State University Extension, Northeast District/Horticulture and Crop Science; Nancy A. Taylor, Erik A. Draper, Stephen Nameth, Joseph F. Boggs, |
Nancy Taylor in the Plant and Pest Diagnostic Clinic (PPDC) reported receiving a juniper sample with both Phomopsis twig blight causing dieback of branch tips, and Phytophthora root rot causing death and decay of the root system. It is not uncommon for plants to be infected with more than one pathogen and symptoms of one disease may mimic, enhance, or obscure symptoms of another disease.
Often, one of the diseases is more serious, as was the case here. Phomopsis twig blight can certainly make a juniper look bad, but it is seldom a killer. As we constantly remind BYGL readers, the best way to sort things out, so a management strategy can be developed, is to send a sample to the C.Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC).
We also stress the importance of considering components of the disease triangle (pathogen, susceptible host plant, environment conducive to disease) to plan strategies to avoid and/or manage disease problems.
The "environmental" side of the triangle plays a pivotal role in managing Phytophthora root rot. Indeed, the pathogen is sometimes tagged as one of the "Dr. Treevorkians" of the soil. It often finishes off roots that are already stressed by an environmental problem, such as heavy moisture caused by poor drainage.
While the landscaper did the right thing by sending the sample, their response to Nancy's recommendation that drainage be improved, was that drainage could not be improved. Unfortunately, such is often the case in landscape installations major changes are beyond the control of the landscape manager. But, at least the landscaper will know what killed the juniper.
Furthermore, when plant selection or site preparation is in their purview, the manager can learn how to avoid the "same darn thing over and over again."