Hostas have become very popular and widespread all over the world. This has increased the demand for any information related to these plants.
To treat petiole and crown rot on the hosta, remove the damaged leaves and petioles. Clean all soil of the fungus bodies and spray the entire plant with a fungicide. Next, drench the entire soil near the hosta with fungicide.
This is a short description of the treatment for this disease. Next, we will go into this issue in as much detail as possible.
What causes crown (petiole) rot in hostas?
Crown and petiole rot of the hosta is caused by a pathogen called Sclerotium rolfsii. This is a rather serious disease that can lead to the death of the plant. Its other name is Southern Blight.
This disease is quite common and affects many crops in addition to the hosta. Once in the garden, the disease quickly spreads and it is almost impossible to get rid of the pathogen completely. However, there are ways to effectively control the disease.
It all starts in a warm and humid season. Usually, Southern blight does not manifest itself before summer. If the summer weather is humid for a long time, traces of fungal origin will appear near the hosta. After that, the spores mature and the life cycle repeats.
What does hosta crown (petiole) rot look like?
The first symptom of Southern blight is yellowing of the leaves. This happens because the movement of water from the roots to the leaves is impaired. Next, the leaves can dry out and become brown and crispy.
A second symptom is leaf petioles drooping. They simply lie on the ground with the leaves. It is as if the bush is falling apart.
If this happens to your hosta, examine the ground around it. Pay particular attention to the base of the petioles.
Sclerotium rolfsii forms a white substance called mycelium on the ground around the stems. It produces white granules resembling small grains. These are the bodies of the fungus that are ready for further expansion.
Also a special feature of this disease is the smell. Get close to the bush and check for the smell of mushrooms or mold.
Pull a leaf petiole that is resting on the ground. It should come off easily and its base should be brown.
Hosta crown and crown (petiole) rot treatment
If your hosta has petiole rot, the first thing to do is to remove the diseased petioles along with the leaves. Just don’t leave them rotting in your yard. Instead, throw them in the trash.
Next, clean all traces of fungus from the ground near the hosta (mycelium, granules, and all rotten tissue). Also, remove the rotten part of the crown using a sharp knife. It is not necessary to dig up the hosta.
Scrape away 1 inch of soil around the hosta. Throw this soil, along with everything else you collected around the hosta, in a garbage bag.
Next, dilute the fungicide in water and soak the soil around the bush well. Water the hosta over the crown with this solution.
Fungicides that are effective against petiole (crown) rot:
- Cleary 3336;
- Mancozeb;
- Products that contain thiophanate methyl;
- Products that contain tebuconazole.
You can also go a little differently. Dig up the hosta and clean it from the soil. Then wash it with clean water. Remove all the rotten tissue and tear off the rotten petioles.
Take a bucket of water and dilute a fungicide in it. Immerse the hosta in water and let it soak for about half an hour. Next, pull the hosta out and shake off the solution. Plant it in a place that is not too wet using well-drained soil.
How do I avoid hosta crown (petiole) rot?
The first thing to do to avoid petiole rot is not to buy diseased plants. If you want to buy a hosta, examine it for symptoms of Southern blight.
Keep your garden clean at all times. Avoid leaving plant debris in the garden to rot. Always remove dead hosta leaves at the end of the season in the trash.
Renew mulch once a season. Use pine bark or compost for mulch. Avoid mulching with material that has not decomposed, such as grass clippings or leaves. Also, do not submerge leaf petioles in mulch, i.e. avoid so-called volcano mulching.
Only plant hostas in drained soil that is rich in organic matter. Do not bury leaf petioles in the ground during planting. The place where the petioles connect to the rhizome should be just above the ground.
Avoid overwatering the hosta. Let the soil around it dry out 1 to 2 inches between waterings. Also, do not plant hostas in areas that are too wet. For example, do not plant a hosta where water runs off the roof.
Also, preventive spraying with fungicide can help prevent the spread of this disease. Spray the hostas and the soil around them once every two months with an aqueous fungicide solution. This should be done starting in early spring and continuing through mid-autumn.
Will the hosta recover after crown (petiole) rot?
The hosta will recover from petiole rot if the rhizome is not too damaged. In other words, if the disease affects the base of the petioles and the top of the crown, the rest of the plant can fully recover.
The size of the hosta also matters. If it is a dwarf hosta with a small rhizome, it has little chance of surviving. But if it is a large variety with a large crown, it can beat the disease.
Most likely you won’t see any more leaves in the current year. But with proper care next spring, the hosta will recover to its former state.
The regeneration process must take place in full shade. If the diseased hosta is growing in partial shade, place an additional shade over it.
Water the hosta with liquid fertilizer. Once is enough to help the hosta heal faster.
Don’t give it too much water. Keep the soil near the sick hosta dry to a depth of 1 inch.
Do not cover it with mulch. The area where the rhizome comes out of the ground should be ventilated and not wet. It should dry out quickly after a rain.
During the season, treat the damaged hosta 1 or 2 more times with a fungicide.