Shasta daisy problem

Question: Hello, in a couple of areas of my garden I’ve had problems with my shasta daisies the past five years. They initially come up vigorous and very healthy looking, but after flowering for a couple of weeks many of them begin to turn brown and shrivel. When I pull them out of the soil I sometimes see little worms on their roots. There are also a lot of little things like wood lice in the soil.

The daisies get about six hours direct sunlight per day. I do not overwater them.  I’d say I lose around 40% of my plants in these 2 areas.

I’d be most grateful for any help you might be able to give me.

Thank you!

responder: Hello,   Replied July 30, 2024, 11:50 AM EDT
response: Hello Philip, I fear your Shasta Daisies have a fungal disease known as Verticillium Wilt.  You can see the the disease has attacked the plant at soil level and through the stem. I have attached a link that you can read that goes into detail about this disease.   The fungus lives in the soil and can remain dormant for years.  Once the fungus is activated due to weather or other conditions that are favorable for its return, it is almost impossible to irradiate.  It can be spread by tools that are infected from the soil, so it is always important to remember to clean and sanitize your pruners.   Shasta daisies are on the list of perennials that are susceptible to this problem.  The only recourse is to plant varieties supposed to be immune to the wilt.  Becky is one variety that many of stated is resistant, but I have no personal experience to vouch for this statement.   I. have also attached a list fro Washington.edu that has a list of herbaceous cultivars that are known to be resistant, so you may have to switch to another type of plant in this area.  https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/cankers/verticillium-wilt https://depts.washington.edu/hortlib/resources/ucdavis_verticillium.pdf I hope this helps provide you some direction. And Thankyou for your question. Kathleen

responder: The Question Asker Replied July 30, 2024, 9:11 PM EDT
response: Hello Kathleen,Thank you for your reply. It is interesting and helpful. I’ve read the links you attached and one thing I remarked on. That is, black-eyed Susans are listed as susceptible to this fungus; however I have them planted right by my Shastas and the Susans have never had a problem ……..? What do you make of that?   Thanks again for your help,   Philip   Sent from my iPhone  On Jul 30, 2024, at 11:50 AM, Ask Extension <<personal data hidden>> wrote:

responder: Hello,   Replied August 14, 2024, 3:33 PM EDT
response: Hello Philip, It is hard to say and curious that the Black Eyes Susan's would not be affected as well.  It is possible  are a resistant variety. Of course, the yellowing leaves I your photo might be completely normal as daisy die back and look best at that point when trimmed flush to the ground, where they will then push out new growth.  I was looking more at the stem issues that your daisy's show.  I forgot to mention that if you cut lengthwise into the stem near the base of the plant and see brown streaking inside, this is a sign of the V Wilt that I mentioned previously.  A similar question about Shasta Daisies also offers some additional insight: “Some common diseases that affect shasta daisies (Leucanthemum x superbum) are alternaria leaf spot, septoria leaf spot, botrytis, powdery mildew, The treatment for any of these is the same. Below are some cultural tips to help reduce fungal disease: Remove and destroy diseased leaves and plants at the end of the growing season.Keep plant tops as dry as possible by applying water to soil, not sprinkling over plants.Rotate planting beds. It is difficult to properly identify the pathogen causing leaf spots. If you experience persistent problems (year after year) with the same type of leaf spot, it may be beneficial to contact your local extension agent a

responder: The Question Asker Replied August 16, 2024, 8:51 PM EDT
response: Thanks again for your reply. Yes, the bottom three inches or so of the stem of affected plants show brown streaks when cut lengthwise. The funny things is the roots are mostly healthy looking when I pull these plants out ........   On Wednesday, August 14, 2024 at 03:33:09 PM EDT, Ask Extension wrote:

responder: Hello,   Replied August 19, 2024, 6:18 PM EDT
response: Hello again,  Since V Wilt is a vascular disease and the fungus enters the plant though the roots, and then travels up where it then attacks the vascular tissue - stems, etc, - and prevents the plant from taking up water and nutrients through their tissue, so the roots don''t initially show signs of the disease.   All the best and hopefully you can find something that is not suspendible to this disease to plant in this area.