The hosta is a stunning ornamental plant. Adding a succulent touch to any garden plot is as simple as planting one of these plants.
Diseases rarely affect Hosta, but leaf-eating pests and insects can threaten its health.
The first signs of visible damage should be interpreted as a call to action.
It’s critical to treat hosta diseases as soon as they appear, as waiting too long to address a problem could result in the plant dying.
I’m about to share details on common hosta diseases and how you can treat them.
I’ll also share some real-life pictures of diseases and pests that the plant is known to affect.
And how to avoid your hostas’ downfall by dealing with them.
You can quickly tell by the outward signs that the first signs of disease are developing on your plant.
So, what are the most common diseases that affect the hosta?
 Hosta Virus X (HVX)
American scientist Lockhart discovered Hosta Virus X (HVX).
The disease is spread by sap on garden tools or hands while pruning or dividing shrubs.
When you use a dirty hoe or your hands to touch healthy plants, the virus enters the plant’s tissue through the cuts and wounds and begins to feed and multiply.
Before the discovery of the virus, yellow spots, tiny flecks, dashes, and rings were mistaken for unusual hosta coloration.
However, it was later discovered that it is a disease that causes stunted growth and curling leaves.
Hosta Virus X (HVX) distinguishing characteristics:
- The heterogeneous coloration of the leaf due to variations in tissue density and coloration;
- Dark green stripes on veins of leaf confirm hosta virus x infection.
- Chlorosis occurs, and as a result, the foliage turns a pale shade of green. Sometimes the vein starts turning yellow in an advanced stage.
- Small, fuzzy spots that look like a mosaic
- Stunted growth of the plant, resulting in dwarfism;
- The flowers’ color is faded, and no ovary can be found.
Immediate action: If an infestation is detected, the entire garden should be replanted as far away from the infected area.
The affected plants should be disposed of as household waste or burned to prevent the hosta virus from spreading to other plants.
Even though Hosta sieboldiana, also known as Siebold’s plantain lily, and its hybrids are virus-resistant, that doesn’t mean they’re entirely free of the risk of infection.
There’s no point in trying to save the plant if a virus has been found because the disease is incurable.
It infects every part of the hosta plant, eventually killing it. I recommend burning the diseased hosta and disinfecting the used tools.
 Phyllosticta Leaf Spot
Indoor and outdoor plants are susceptible to Phyllosticta Leaf Spot, also known as brown spot disease.
High humidity and temperatures above 77°F (25°C) are ideal for the Phyllosticta fungus.
- Large brown spots appear on the surface of plant leaves;
- The spots gradually blend together to form a large lesion area.
- The fungus appears as a white or yellowish plaque on the surface of the spots;
- The disease frequently affects both the leaves and the flower stems of hostas;
- Infected plants gradually dry out and die.
- Brown spots appear on the leaves, which then crack and fall apart.
- The advanced stage of the Phyllosticta leaf spot leads to the death of the plant.
Reduce the frequency and volume of watering of the hosta by burning leaves and stems with fungal spore centers.
You should discard the entire plant if it is severely damaged.
You should remove the diseased hostas from their original locations to prevent them from infecting other plants in the area.
Copper-based fungicides are effective in combating the disease. Spraying every 10 days until flowering begins is the treatment for brown spot disease.
 Gray Rot
Gray rot fungi are omnivores, as are their hosts. Herbaceous plants, flowers, and fruit and berry plants are all affected.
In addition to being widespread, the disease can be deadly for your hosta.
The plant will die if you do not take appropriate measures promptly.
The botrytis fungus grows mycelium on the plant and releases spores that are carried by the wind to other nearby plants.
Gray rot symptoms differ depending on the stage of the disease’s development.
- Botrytis spores are visible in the early stages of infection as blotchy, deformed, and dried leaf edges and tips.
- The disease’s early stages begin with the decay of the hosta’s leaf tips.
- Advanced stage: the rot has spread to every part of the leaf.
- Initially, treatment consists of spraying fungicides on the diseased leaves.
- You need to destroy the affected plant if the infestation is severe.
Preventing gray rot is much easier than treating it once it has occurred.
Apply the first soil treatment early in the spring when the soil is still loose.
Spray copper-based contact fungicide on planting sites using a sprayer.
 Root, Stem, and Collar Rot
It’s a fungal rot caused by Phytophthora. It’s a fungus that lives in the soil and attacks plants by infecting the roots and rhizome.
These fungi can remain inactive in cold weather and activate when the environment becomes warmer and more humid.
It causes a rot at a much slower rate than bacterial soft rot. This time, the odds are in your favor to save the pieces.
It is nearly impossible to predict root rot at the early stages without first identifying and inspecting the root system. The roots will rot, causing some symptoms to appear above ground.
The discoloration of the leaves is a surefire way to spot root rot.
The leaves first turn yellow from the edges to the center, then discolor and dry out before falling off.
There is no such thing as a treatment for this condition whatsoever.
Do not use soil from beneath the plant, and do not transplant infected shrubs or those suspected of being infected.
To prevent the fungus from spreading further, remove all diseased hostas from the garden and dispose of them properly.
- Treatment of the early stages of the disease entails digging up your hosta and Removing any soft roots and rhizome material that isn’t hard and white, like coconut meat.
- Once clean, use hydrogen peroxide on it a couple of times then let it dry thoroughly in the sun.
- Use a systemic fungicide like Liquid Copper Fungicide to treat the problem. Phyton could also be a good option.
- Now, I’d dig out the soil in that hole and replace it.
- If the infestation is too severe to be treated, dispose of the entire plant and the surrounding soil to prevent it from spreading further.
Copper Sulfate And Bordeaux Liquid Spraying Are Effective
However, putting the plant’s health at risk is not a good idea. When the first leaf turns yellow, dig up the hosta and thoroughly examine for any signs of root rot.
Cut the affected areas with a sharp knife, and treat the cuts with fungicides or crushed activated charcoal.
Do not replant the diseased hosta until it has dried out for 1-2 hours, and then plant it in a new container.
 Bacterial Soft Rot
Bacterial soft rot can be caused by various bacteria and typically occurs when a leaf has been damaged.
Winter icing can also leave these types of wounds. It usually appears during the warming period after a frost.
The decaying cuttings and lower leaves give off a distinct rotten smell that you won’t be able to mistake for anything else.
You will see some visible damage to the plant. This explains why the hosta’s leaves have developed new brown spots.
Plants that are infested should be removed and destroyed.
Ensure all tools that have come into contact with the plant are thoroughly cleaned, and wash your hands and gloves.
Because the bacteria spreads slowly and only to the damaged areas, removing the entire garden isn’t necessary for this situation.
The disease affects healthy leaves and neighboring shoots quickly and is widespread.
The most vulnerable plant species are those that require a lot of shade and a lot of moisture.
When a hosta is infected, you’ll notice small round-shaped brown spots on the leaves that grow larger and have darker borders, much like rust on the plant.
The spots literally “tear” the leaf, leaving only the tough veins intact.
Get rid of diseased leaves, lower humidity levels, and ensure plants have adequate ventilation (ensure plenty of room for air circulation).
Then, use a fungicide to keep the remaining healthy leaves from becoming infected again.
 Crown rot (Southern Blight)
Petiole rot, also known as crown rot, is a dangerous fungal disease.
Petiole rot, also known as crown rot, is a dangerous fungal disease. It is caused by a fungus called fusarium, which rots the roots from within.
It isn’t usually a big deal until it gets into the crown, at which point you have to cut it out until you get to clean tissue.
Fusarium can be a bigger problem in potting soil that dries out too much between waterings, but it usually has to get on the plant or soil somehow for it to become a significant issue.
Yellowing and wilting of the leaves along the outline are the primary symptoms.
At the base of the leaf, it becomes floppy, spongy, and rotten.
Leaves too large to support themselves can “fall off” the main shrub altogether.
You may also visually identify fungal filaments (mycelium) that are white.
As the fungus grows, it spreads tiny round sclerotia seeds, eventually covering the whole plant.
When it’s cold outside, the fungus is dormant, but when it gets warmer and wetter, it comes to life.
There is no treatment for this disease. Avoid using the old soil for replanting.
To stop the fungus spread, eliminate or destroy any infected hosts in the garden.
You should now be able to identify and treat common hosta diseases. If you have any questions or suggestions, please share them with me.
Other Diseases to Be Aware of
Nematodes about 2 mm in diameter and round cause brown spots and stripes on the leaves. You can’t tell that there is an infestation in the early stages.
Nematodes might be stopping the hosta from growing, but you can find out for sure with a simple test.
Chop up a leaf and put it in a glass of water for 15 to 20 minutes. If the doubt is correct, the worms can be seen in the water when there is light.
Nematodes live as parasites in the plant’s tissues, causing the plant to become misshapen and spreading harmful viruses.
Nematodes are hard to eliminate because pesticide sprays kill the adults but not the eggs.
To get rid of the pest, use a ready-to-spray (Amazon link) nematode control solution.
In addition, you must adjust the watering schedule for your hosta if you want it to grow correctly and without issues.
Tobacco Rattle Virus
TRV is common in North and South America as well as in Eurasia. It affects up to 400 varieties of plants.
Potato yields can be reduced by up to 10%, and tuber quality can be compromised due to the virus.
Its vectors are leaf nematodes, which harm hostas as well. Symptoms of a virus infestation include:
Hosta shows a wide range of symptoms when infected with this virus, especially on the leaves.
Most of the time, the leaves are smaller, and some have mosaicism, mottling, wavy edges, and dead spots.
In addition, their veins and stems can rot. Dwarfism results while average plant growth is inhibited and cuttings and branches are shortened.
Nematodes can also cause damage to rhizomes. The symptoms usually get less severe when temperatures exceed 20 degrees Celsius.
Leaf Curl Virus
When the curl virus gets into a hosta, it can cause the leaves to shrink, tear, and get spots that look like stars.
Cell death and eventually holes develop in their place over time. Since there is no cure for the virus, sick plants are dug up and thrown away.
After the procedure, ensure that the soil and tools are disinfected.
Rust on Hosta
The leaf margins of diseased varieties have a yellow ring around them. Initially, the disease appears as large yellow spots turning rusty in color.
A lack of humidity is the most common cause of the disease. Increase the watering, keep an eye on the water quality, and spray the plant in the morning and evening when the sun goes down.