Hi, friends! Today I will tell you about the most common diseases of hostas and how to deal with it.
| Disease | Symptoms | Treatment |
| Anthracnose (Colletotrichum) | Red-brown spots on leaves. | Prophylactic spraying with fungicides. |
| Petiole rot (Sclerotium rolfsii) | Yellowed leaves, broken petioles at the base. | Removal of the damaged part of the plant, treatment with fungicide. |
| Fusarium root and crown rot (FRCR Fusarium hostae) | The center of the crown and the rhizome are light brown. | Removal of the damaged part of the plant, treatment with fungicide. |
| Bacterial Soft Rot (Pectobacterium) | The petioles and center of the crown become soft and watery, with a bad smell. | Remove the damaged part of the plant and treat it with a fungicide. |
| Hosta Virus X (HVX) | Green spots on leaves, twisting leaves, slowing growth. | Remove infected plants. |
| Nematodes (Aphelenchoides spp.) | Dry stripes on the leaf. | Remove infected leaves. |
| Phytophthora Foliar Blight | The leaves are partially turning brown. The bush is falling apart. | Remove the damaged parts of the hosta. Treat it with copper fungicide. |
| Phyllosticta Leaf Spot | Brown spots with holes. | Spray hosta with cooper fungicide. |
| Cercospora Leaf Spot | Brown spots with a reddish-brown center. | Spray hosta with cooper fungicide. |
1. Anthracnose
During warm, rainy summers, anthracnose thrives. This fungal disease can seriously harm hostas.
Symptoms:
- Brown spots on leaves with dry centers.
- Spots grow, merge, and may cause leaf death.
Treatment:
- Remove and discard infected leaves; don’t compost them.
- In early stages, spray Phyton fungicide on the plant and surrounding area.
- For severe cases, use systemic fungicides with chlorothalonil.
- Regular preventive spraying helps stop future outbreaks.
Read more: How Do You Get Rid Of Anthracnose?
2. Petiole rot (Southern Blight)
Petiole rot is one of the most dangerous hosta diseases, often killing plants quickly. Prevention and early detection are key.
Warm, humid weather (above 80°F) activates dormant spores, which attack the base of petioles.
Symptoms:
- Yellowing leaves.
- Petioles break at ground level, turning reddish early on.
- Yellow granules near the rhizome.
Treatment:
- Keep mulch 1–2 inches away from petioles.
- At first signs, clean the plant and replace the topsoil with fungus-free soil.
- Apply a fungicide like Fungo or products with tebuconazole to the plant and surrounding soil.
- Spray all garden plants regularly with systemic fungicides.
- If the plant is severely infected, remove it with the surrounding soil, then disinfect tools and the area thoroughly.
Read more: How Do You Treat Petiole Rot On Hostas?
3. Fusarium root and crown rot (FRCR)
Fusarium Root and Crown Rot (FRCR) is a serious, widespread disease. Once it spreads, saving the hosta is nearly impossible. The fungus lives in the soil and easily enters through wounds on the plant.
Early Signs:
- Slow spring growth.
- Fewer, smaller leaves compared to healthy plants.
Advanced Symptoms:
- Leaves turn yellow and wither.
- Crown center turns light brown.
Treatment:
- Inspect roots carefully before buying hostas.
- Use clean tools when dividing plants and treat wounds immediately.
- If caught early, remove infected parts and soak them in a fungicide with thiophanate-methyl.
- Replant in a pot with sterile, peat-based soil. Recovery is possible over time.
4. Bacterial Soft Rot
Bacterial soft rot bacteria stay dormant in the soil until the right conditions appear. They often infect hostas through winter frost damage. Warm, humid weather (above 80°F) triggers the disease.
Symptoms:
- Yellowing leaves with limp petioles lying on the ground.
- Crown becomes mushy and watery.
- Strong odor like rotting fish.
Treatment:
- Dig up the hosta and wash it thoroughly.
- Cut out infected parts with a sterile knife.
- Let it dry in the shade for a few hours.
- Soak in a fungicide solution like Phyton 35.
- Replant in fresh, clean soil in a new spot or pot.
5. Hosta Virus X (HVX)
Hosta Virus X (HVX) has no cure. Discovered in 1996, its origin is still unknown.
The virus spreads through pests feeding on infected plants or by using the same tools on both infected and healthy plants. It often stays hidden for a year, allowing the disease to spread unnoticed.
Symptoms:
- Green spots or mottling on leaves.
- Leaf deformation, yellowing, and curling.
- Slower growth and smaller plant size.
Treatment:
- Avoid buying plants with suspicious symptoms.
- If a plant is infected, dig it up and burn it to prevent spreading.
Read more: Hosta Virus X
6. Leaf Nematodes
Leaf nematodes are tiny worms that spread during rainy weather. Raindrops carry them onto hostas, where they enter through wounds or natural openings. Once inside, they feed on plant cells and multiply.
Symptoms:
- Dry streaks running along the length of leaves.
- In severe cases, multiple streaks cause leaves to decay.
- Symptoms appear a few months after infestation.
Treatment:
- Remove and burn affected leaves and stems immediately.
- Disinfect all pruning tools.
- In late summer, cut green leaves and stems before they yellow to reduce nematode populations. Dispose of them properly.
Read more: How do you treat foliar nematodes?
7. Phytophthora Foliar Blight
Phytophthora foliar blight is a common fungal disease that spreads quickly in warm (70°F+) and humid conditions. It can severely damage or even kill hostas.
Symptoms:
- Large brown spots on leaves that expand, causing them to wither and die.
- Petioles may turn brown, and the plant may become weak and fall apart.
Treatment:
- Water only when the soil is dry 2+ inches deep.
- Remove the hosta, cut off rotting parts, and clean wounds with a copper fungicide.
- Let the plant air-dry in shade for up to 1 hour.
- Discard severely damaged leaves and spray remaining foliage with a broad-spectrum fungicide.
- Replant in well-drained soil in a location with less moisture buildup.
8. Phyllosticta Leaf Spot
Phyllosticta Leaf Spot is a fungal disease that affects hostas and many other plants. It becomes active when temperatures reach 77°F (25°C).
Symptoms:
- Brown spots form on leaves with a white fungal center.
- Spots grow, merge, and create holes until the leaf dies.
- Stems may also develop brown patches.
Treatment:
- Water only when the top 2 inches of soil are dry.
- Avoid planting in humid, poorly ventilated areas.
- Spray with a copper fungicide solution and repeat after one week.
- Remove and discard severely damaged leaves.
9. Cercospora Leaf Spot
Cercospora Leaf Spot is a fungal disease that mainly affects hosta leaves, especially during very hot weather. Stems and crowns are usually unaffected.
Symptoms:
- Brown spots with yellow edges and a reddish-brown center.
- Spots increase until the leaf dies.
Treatment:
- Spray regularly with a copper fungicide, repeating every 7–10 days.
- Remove and discard dead leaves to prevent spreading.
Other diseases
Impatiens Necrotic Spot Virus (INSV)
INSV is spread by thrips. Symptoms may take time to appear but usually include white patterns on green leaves and possible leaf necrosis.
Control: Sterilize tools and use insecticides to manage thrips.
Tomato Ringspot Virus (ToRSV)
ToRSV causes yellowing similar to chlorosis. It spreads through plant division and nematodes.
Control: There is no cure. Remove and destroy infected plants to prevent spreading.
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My hosta leaves (and some impatient leaves on a nearish patio) have tiny pin holes in them. What could this be? A mite of some sort?
I wish I could insert a picture.
Most likely these holes are left by small snails that are still growing. In my case, iron phosphate helped.
What’s wrong with my patriot hosta? All my other hostas are fine.
Hi Mary,
It looks like your hosta has been damaged by some insects. Spray the leaves with insecticide soap.
I hope this will help. I’m happy to answer any other questions you may have.
My garden is made up of pretty much cheap hostas, nothing fancy, I just split them up and then replant. I love them! I added new dirt with fertilizer earlier in the spring just as the plants were coming up. Two years ago I purchased a variegated Hosta, I don’t know the name but over the winter something happened to this variety of hosta. (We live in zone 3 where winter can be brutal.) Just a tiny bit of each plant, tips of one or two leaves, emerged from the soil and then the entire plant stopped growing. When digging in the soil, I found an abundance of roots, and toward the center of the plant, it was a yellowish color with tiny like stringy whisps. A few of the other larger hostas nearby are bare toward the center with larger leaves emerging and coming up on the outside of the plant. Not sure what happened. I will send photos.
Hi Maureen,
Your variegated hosta may have been damaged by frost and started to rot. Or you may have purchased a diseased hosta.
Dig up the hosta and check for rot. If rot is present, remove it and treat it with a fungicide. Plant the hosta in sterile soil and water it with liquid fertilizer and maybe it will start to grow, but you should not hope for a miracle. In the future, I recommend planting more vigorous varieties.
I hope this helps, I’m waiting for updates from you.
What’s up here??
Hi Sharon,
It looks like a fungal disease. Spray the hosta with a copper fungicide.
To prevent this from happening next year, spray the hosta with a fungicide as soon as the leaves appear. Repeat the spraying after a month.
I hope this helps. I will be happy to answer any other questions you may have.
Would anyone be able to identify the problem with my hostas? I planted them in the ground last Spring and this same type of rotting (maybe a fungus?) occurred. They died back to the ground and I assumed they were goners, but lo and behold, they reappeared again this Spring! I planted them in pots this time, in case slugs and snails were the issue, but they have made their way up into the pot. Thanks for the help!
Hi Aimee,
This is Southern Blight. This disease affects the leaf petioles and can spread to the rhizome.
To remedy the situation, dig up the hosta and clean it off the ground. Remove the rotten part with a sterile knife. Spray the wound with a copper fungicide or a product containing tebuconazole.
Then plant the rhizome in the soil away from the previous location. After a while, the hosta will recover. In the future, avoid overwatering and planting the hosta too densely.
Also avoid burying the hosta stems in the soil or mulch. The place where the stems emerge from the rhizome should be at soil level but not in the soil.
Just wondering what’s happening here. All of my hostas have this going on.
Hi Allison
It’s a sunburn. Hosta does not like direct sunlight, especially in the heat of summer.
Create a shade over it for the summer and water it with enough water. Sometime in September, the shade can be removed.
Got these hostas from neighbor and they did fine the first year. Cut them back to ground level and they over-wintered without mulching. Came back this year and they grew back nicely until we had about 2 weeks of temps in the 90s. Are these leaves showing fungal disease?
Hi Jann
It looks like heat stress and lack of water. Provide it with full shade for the heat wave and give it enough water but avoid overwatering.
I don’t see any signs of a fungal disease. Remove the lower dry leaves and that’s it.
The leaves of several of my hostas, different varieties have become waxy, shiny, slippery. We have had a lot of rain.
Hi Rick
This is a disease caused by excessive moisture and overwatering. I recommend that you remove severely damaged leaves and spray the hostas with a fungicide.
About half of my hostas have small holes with dry edges. In searching online for help I came upon your “most common diseases” information. I’m thinking my plants are suffering from Phyllosticta Leaf Spot so I will be trying the copper fungicide.
Thank you for your help.
Hello Candida
I’m glad you found the information here useful. I recommend that you also protect your hostas from snails. Such small holes are left by snail babies. Use iron phosphate for this purpose.