Problems with Liriope - Ask Extension
My daughter's variegated liriope has spots all over it. Doing some research, the two most common issues are Anthracnose and root rot. None of the pict...
Knowledgebase
Problems with Liriope #864785
Asked April 16, 2024, 5:16 PM EDT
My daughter's variegated liriope has spots all over it. Doing some research, the two most common issues are Anthracnose and root rot. None of the pictures I saw of those issues looked exactly like my daughter's issue, though the description seemed a little like Anthracnose. Can you tell me what it is and what we should do about it please?
If it's Anthracnose, Clemson says to get rid of the debris and put a fungicide on the new growth as a protective measure. Does that mean just cut back the damaged leaves or does it mean digging up and getting rid of the plants? And if we should use a fungicide, is there one your recommend (not necesarily a brand, but what should we look for)?
Montgomery County Maryland
Expert Response
This is indeed a classic symptom of anthracnose infection, which can be quite commonplace on Liriope, especially in wet years or after frequent irrigation that gets the leaves wet. Fungicide use might suppress future infections, but comes at a risk of harming other organisms (even though the pesticide targets fungi), and in our opinion is not worth attempting in this situation. (Fungicides also don't always work completely, so some re-infection is still possible. Treatments would require repeat applications, likely well into summer, and rain can interrupt a re-treatment pattern and allow some infection to take place.)
Instead, cut back all the old foliage and let the new growth emerge and cover-up the stubble. While there is no guarantee it will remain leaf spot-free, if we have drier weather or if the plants are not watered with sprinkler too often, the level of reinfection should be minimal. Usually, Liriope foliage from the prior year is cut back around March (leaving a couple inches of stubble off the ground), in order for this to be done before there is a risk of accidentally cutting into emerging new growth, as might happen this far into spring. Even so, if a few new leaves are cut, it's not serious damage and the plant should eventually produce replacement foliage that will emerge later. Throw out the removed debris since a home compost pile likely won't get hot enough to kill infectious spores.
You do not have to dig up and remove the entire plant unless you prefer to replace them. (Root rot would have resulted in leaves pulling up fairly easily since they detach from the dying roots, and in that case, the entire plant would best be removed. That does not appear to be the case here, though.)
As a potential replacement, there are some species of sedge (botanical name Carex), for example, that look almost identical to Liriope foliage, though they won't have the purple flowers that Liriope has. Some sedges are native, but those that are variegated (striped in yellow or cream) are non-native species. Depending on the site conditions (how much summer sun, soil drainage, deer browsing risk, etc.), there are plenty of other alternatives to plant of similar stature, though few other plants will provide a grassy look, especially with leaf stripes, if that is the preferred aesthetic.
Miri
Instead, cut back all the old foliage and let the new growth emerge and cover-up the stubble. While there is no guarantee it will remain leaf spot-free, if we have drier weather or if the plants are not watered with sprinkler too often, the level of reinfection should be minimal. Usually, Liriope foliage from the prior year is cut back around March (leaving a couple inches of stubble off the ground), in order for this to be done before there is a risk of accidentally cutting into emerging new growth, as might happen this far into spring. Even so, if a few new leaves are cut, it's not serious damage and the plant should eventually produce replacement foliage that will emerge later. Throw out the removed debris since a home compost pile likely won't get hot enough to kill infectious spores.
You do not have to dig up and remove the entire plant unless you prefer to replace them. (Root rot would have resulted in leaves pulling up fairly easily since they detach from the dying roots, and in that case, the entire plant would best be removed. That does not appear to be the case here, though.)
As a potential replacement, there are some species of sedge (botanical name Carex), for example, that look almost identical to Liriope foliage, though they won't have the purple flowers that Liriope has. Some sedges are native, but those that are variegated (striped in yellow or cream) are non-native species. Depending on the site conditions (how much summer sun, soil drainage, deer browsing risk, etc.), there are plenty of other alternatives to plant of similar stature, though few other plants will provide a grassy look, especially with leaf stripes, if that is the preferred aesthetic.
Miri
