Hostas are some of the most popular shade-loving plants. They come in a variety of sizes and colors and make a bold statement to any garden. However, hostas are susceptible to many diseases; here’s how to identify them.
How do you identify hosta diseases? Hosta diseases will affect different parts of the plant, such as the roots, crown, and leaves. Look for soggy areas of the plant, brown rot through the roots, and yellow spots on the leaves.
What does hosta disease look like?
There are many forms of hosta disease but most result in some sort of change to the plant. The most common is discoloration of the leaves but you may also see your plant looking limp or stunted in growth.
Some diseases will attack the leaves of a Hosta plant while others go for the root structure. If you suspect disease, dig through the soil to ascertain how widespread the disease is. This can include soggy roots or brown rot around the roots and crown.
Types of hosta diseases
Also known as Southern Blight, this is one of the most common hosta diseases and, unfortunately, one you want to avoid at all costs. While there may still be a chance of salvaging your hosta, you need to act very quickly after you discover it.
Petiole rot spreads from a fungus in the soil. This fungus can lay dormant for years so you may not even be aware that it is infecting your plants. If you do discover your hosta suffers from Petiole rot, you will want to remove all the soil in the area so as to not infect future plants.
Petiole rot is most common in southern regions as the fungus won’t start to grow until the temperature surpasses 80 degrees Fahrenheit. When it does multiply and start to attack your hosta plant, you will see yellow leaves as well as yellow specks around the root structure. In particular, the base of the hosta will start to break off.
Another common hosta disease is Anthracnose. It spreads quickly in warm, humid conditions, so watch out for it if you get a lot of rainstorms in the summer.
The disease is spread by fungi spores and while it is common, it thankfully won’t result in the death of your plants. As long as you identify it in its early stages, you can take action to keep your hosta healthy.
The most common symptom of Anthracnose is brown or yellow spots on the leaves. The middle of these spots will be dry but if not treated, the spots will spread over the whole leaf.
Fusarium root and crown rot
In its abbreviated name, this disease is also known as FRCR. It spreads very quickly and unfortunately, you may not be able to save the plant although you can act to limit the disease from spreading to other plants in the area.
FRCR attacks the crown of a hosta plant, which is why it is so deadly. Once the crown of the plant becomes weakened, the entire plant will suffer.
To diagnose FRCER look for a light brown color in the crown. As a result of infection, the leaves on your hosta plant will turn yellow and wither.
Finally, if you dig the plant up, which you should minimize the spread to other plants, you will see that the rhizome roots are smaller and the center of the rhizome area has a large, brown rot area.
Hosta Virus X
There are some viruses specific to plants, as is the case with Hosta Virus X, also known as HVX. It was first found to exist in 1996 and there is no known cure for it.
HVX spreads from an infected plant to another healthy plant, usually carried by insects. You may also accidentally spread the disease if you use the same tools on a sick plant and don’t wash them before using them on a healthy plant.
To diagnose HVX, look for green spots on the leaves. The leaves may also curl at the edges and have a yellow discoloration.
Bacterial Soft Rot
This is another disease that spreads through the ground. It is particularly deadly because it targets the center of the crown, which then leads to a very weakened plant.
One of the most common ways that bacterial soft rot spreads is when you divide your hostas. If you don’t use clean materials, you can inadvertently spread bacteria.
As you can guess from the name, the most common symptom of bacterial soft rot is a mushy or soft crown. The petioles of the hosta plant will be soft and the leaves will turn yellow. You may even notice a rotten fish smell that signals a decay in the plant.
Nematodes are not specific to hostas as you can find them infesting other plants. These are small worms that move around in the water so they become more abundant after it rains.
After water carries nematodes to your hosta plants, they will work their way through the pores of the leaves and begin to multiply, attacking from within.
The most common symptom of nematodes is large brown streaks on the leaves. These streaks will appear more and more as the infestation spreads, eventually leading to leaf rot.
How do you prevent hosta disease?
No matter what you are doing with your hosta plants, if you are using a shovel or scissors, always thoroughly clean your tools before and after you use them around your hosta. Many diseases are transferred from plant to plant through tools.
When planting your hostas, keep in mind how quickly they will grow. Too much overcrowding can allow diseases to move from plant to plant.
If you find your hostas becoming too close to each other, dig the plants up and divide them. When doing this, however, be sure to clean your materials first.
While bark mulch is an excellent addition to many gardens, as it retains moisture and slowly leaks it back into the soil, you want to be careful about where you place it. For hostas, don’t put bark mulch directly next to hosta stems.
The extra moisture in the bark mulch can lead to high humidity and an overly moist environment. As a result, bacteria and fungi can spread to the stem and roots of your hosta, which will weaken the plant.
How do you treat hosta disease?
Remove infected area
There are many hosta diseases that spread slowly enough that you can simply target the infected areas and still salvage the rest of the plant. However, you want to act as quickly as possible before the inspection spreads too far.
Always use clean scissors or shears so you don’t spread more disease, and always wash them really well after use. Remove any leaves that are discolored and place them in your garbage, not your compost.
Cutting off part of the roots, or rhizomes can be a bit trickier, but still possible. Gently dig through the soil and remove any soft, mushy, or discolored areas. Again, place them in the garbage and not your compost or yard waste bin to avoid the further spread of the disease.
Remove entire plant
There may come a time when you have to accept defeat and recognize that your hosta plant won’t make it. Some hosta diseases can’t be cured, and many spread so quickly that they target the entire plant.
In this case, dig up the entire plant and throw it in the garbage. While this can hurt to do, you will be saving the rest of the plants in the area.
Be sure to dig up the soil around the root structure and remove this, too. Many fungi lay dormant in the soil and will spread to other plants or newly-planted hostas if given the chance.
What is wrong with my hosta leaves?
Thanks to their size, hosta leaves are usually the first indication that something is wrong with the plant. Many diseases will leave hosta leaves with brown or yellow spots.
Other symptoms can include curled edges on the leaves and brown stripes. You may notice the leaves are limp or fall off easily.
After you notice these symptoms, investigate further to determine what the issue is. You should also look more closely at the crown and the root structure to determine if your plant can be salvaged or not.
What does blight look like on hostas?
Blight is a common fungal disease that can infect hostas and other plants. The most common symptom of blight is yellow or brown spots on the leaves that grow larger if left untreated.
Hosta blight will suck up too many nutrients in the leaves, leading them to die and fall off. To prevent blight, don’t overwater your hostas and if you see signs of blight, remove the infected leaves immediately and place them in the garbage.
While hosta plants prefer shade they don’t like to be waterlogged. Pay attention to water levels and humidity as these can lead to ideal conditions for diseases to spread. While you may be able to salvage your plant by removing the affected area, some plants need to be removed altogether.