Roots, Shoots, Fruits & Flowers: Iris Leafspot, Swamp Lily Fungus & Stinkhorn Fungus and Oyster Mushroom

Swamp lilies.

Early stages of iris leafspot. Photo: Lori Dupre.

Iris Leafspot

Lori examined her irises and then sent this email, “Here is two updated pictures of the same blade. One side white spots and other side white spots with a darker green section that looks wet but is dry to the touch. It is on a few blades in the stand. Thanks.”

Extension websites from Iowa and from Virginia identify this condition as “iris leaf spot” or ILS. Paula Flynn, Plant Pathologist of Iowa State University Extension & Outreach writes about the cause of ILS, “The disease is most severe in mild, damp weather, especially in sites where air movement is poor and diseased leaf debris has been allowed to accumulate.”

Several AgCenter articles mention using fungicidal sprays to prevent these infections, but these sprays fail to cure the infection once it is observed.

However, a gardener can use a fungicidal soil drench, an easier method of application than spraying. The process entails mixing the fungicide, per label directions, in a bucket and then pour the fungicidal solution around the base of the azalea. This treatment can be used for other ornamental plants for fungal protection and would be systemic and last longer than a spray.

The disadvantage of a drench would be the lag time because the plant will take of the fungicide through its roots and then the treatment will spread in the plant.

  • Here are products labeled for fungicidal soil drenching:
  • Bayer Advance All-in-One Rose and Flower Care™
  • Bonide Rose Rx Systemic Drench™
  • Bonide Infuse Systemic Disease Lawn & Landscape™
  • Ferti-Lome Halt Systemic Rose, Flower, Lawn Ornamental Fungicide™
  • SA-50 Thiomyl Turf and Ornamental Systemic Fungicide™.

Again, always read and follow label instructions for safe and effective pesticide treatments.

Iris leaf spot.

Fungal leaf spot on crinum lilies. Photo: Jo Hines, Master Gardener.

Swamp Lily Fungus

Rebecca has a similar complaint about her swamp lilies, “We have a yard full of swamp lilies (crinums I believe is the correct name). They got a fungus back in the fall and we sprayed with the fungicide you recommended. Of course, then, that week of low temps [in December 2022] froze the plants. We removed all the frozen mushy leaves. Now they are coming out of the ground with the fungus. Do we just keep them sprayed?”

Dr. Raj Singh, the AgCenter’s “Plant Doctor,” shared his thoughts about the infection in the photo, “It is either cercospora or colletotrichum. Remove severely affected foliage and spray with fungicide containing myclobutanil or propiconazole as an active ingredient.” The drench recommendations above would be another treatment for ILS.

Stinkhorn fungus.

A stinkhorn fungus. Photo: Stacie Pearce.

Stinkhorn Fungus

Stacie sent a picture of a fungal growth in her yard and asked, “This fungi is growing in my back yard, this is the second I’ve found. My concern is can it harm my dogs if ingested?”

On the same day, Raina shared some pictures of her fungus and wanted to know, “My mother, Ramona Wilber, who lives on the southern outskirts of DeRidder, sent me the attached pictures of a fungus in her yard. She has lived there for about 35 years and this is the first time she is seeing a fungus like this.

Neither of us were familiar with it, we attempted a Google search. Unfortunately, there are just too many options of what it could be. We hope that you or someone you may know will be familiar with this type of fungus and can tell us something about it.

There are more of the bulb-like pods from which this one sprouted. We are concerned that this is a non-native invasive fungus that could possibly be poisonous. If so, it would be nice to know the best way to deal with removing them so they do not return. We also do not want the kids or pets to get sick if they accidentally come in contact with them.

Any assistance you can provide in this matter would be greatly appreciated.”

Both Stacie and Raina have stinkhorn fungi (SHF), a native fungus which decomposes organic materials. A search about the toxicity of the SHF is unclear. Some online sources say there is toxicity, and others say there is NO toxicity. With this lack of a clear answer about SHF safety , the best path is to treat SHF with fungicides to avoid contact.

Oyster mushroom.

Oyster mushrooms. Photo: Ponchartrain Mushrooms, Slidell, LA

Oyster Mushroom

Melvin shared a picture of a mushroom like the one below via text message and wanted to know about its edibility.Mr. David Lewis, a professional mycologist, helped with Melvin’s question, “It appears to be the oyster mushroom, Pleurotus ostreatus. However, without seeing the underside, this is an educated guess. Oyster [mushrooms] are edible.”

DISCLAIMER: Do not eat any mushroom, unless you are absolutely certain of its identification. Be sure you KNOW the identity of a mushroom, and that it is safe, before eating it. When in doubt, have any wild mushrooms checked by an expert before eating them.

If you want to contact Roots, Shoots, Fruits, and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337.284.5188 or

“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”

3/2/2023 10:22:48 PM
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