Diagnosing plant disease can often be a tricky game. If I’m brought a small portion of a plant or sent a picture it is hard to get the full picture. I can tell you what I find, but without the full picture of what is going on with the plant it is hard to know if my discovery is the causal agent or not. Much like when you go to the doctor and are asked a sequence of questions to narrow down what may be going on with you, there are several questions that need to be answered to figure out what is negatively affecting your plants. These questions may include how much water the plant receives, what have the weather conditions been, how old is the plant, do you fertilize and/or when, etc. Recently, I needed some plant tissue to test out modifications that were made to my microscopes here at the Extension office. I went outside my office and sampled the Liriope (also called Lilyturfs and Monkey grass).
Much to my surprise, the damaged tissue that I collected was infected with both Anthracnose and Bipolaris. Each of those pathogens are fungal, and cause lesions on the surface of the host plant tissue. It would have been easy to merely say that both of these diseases were causing the necrotic or dead tissue on this plant; however, this would not be correct. The necrotic tissue could be a result of the extremely dry conditions we witnessed over the summer that went unnoticed or is just now displaying the damage. It could be freeze damage from the extreme cold weather we witnessed at the end of December.
In this particular case, an environmental factor, such as weather, has caused the dying tissue, and the pathogens are saprophytic or secondary. The rain we have seen lately and warmer temperatures creates a more favorable environment for diseases. However, even though the pathogens in this instance are saprophytic they do need to be managed so that the disease density does not increase as temperatures rise in the spring and summer which could eventually cause a lot of damage. The key will be to remove the damaged tissue and dispose of the clippings by cutting off all of the damaged leaf blades individually or mowing the liriope back enough to remove the infected area.
As with most anything, managing disease is made much easier through early detection and keeping your plants healthy so that their natural defenses can fend off diseases. If you happen to notice something off with your plants then keep an eye out to what has been going on environmentally, have an idea what all you have done with your plant, and feel free to contact the Extension office for a site visit, drop off a sample, call at 478-986-3958 or email brennan4@uga. edu.
