Rust Spots on Hosta Leaves [Causes & How to Fix]

You are an excellent plant keeper, but something is wrong, and you are unsure how to fix it. What are you supposed to do when your hosta is sporting uncomely red and brown spots?

Rust-colored spots on hosta leaves are a common sign of fungal disease and other possible issues, including infection, pest infestation, or lack of nutrients. The best thing to do is inspect the plant thoroughly to identify the problem and treat it accordingly.

In the rest of the article, we will discuss the possible ailments of your hosta and how to cure it in more depth. Do not despair – your hosta will be right as rain in no time!

Option One: Fungal Disease

What It Looks Like

Fungal disease is a pesky occurrence but not unusual. If your hosta is suffering from fungal rust, the spots on the leaf will be small but brightly colored yellow, orange, or red. Upon close inspection, you should notice the powdery consistency of the dots affecting your leaves.

One way to ensure your plant has contracted a fungal disease is to take a tissue and gently wipe one of the leaves of your plant; if the color of the spots has transferred to the tissue, you are likely dealing with fungal rust.

What Causes It

If your plant has a fungal disease, it can indicate a lack of care. Healthy hostas can fight off fungal rust better, so if your plant is infected, you should probably re-evaluate your nurturing. Thankfully, there is a simple cure for fungal disease and a few easy ways to prevent the condition from returning.

How To Treat It

Removing and properly disposing of all leaves affected by fungal rust is essential. The fungus spores spread through the air, so you must be very careful to put the affected leaves in airtight bags far away from your other plants.

If you would rather not remove entire hosta leaves, it is possible to cut out the part of the leaf affected by the fungus while leaving most of the leaf intact.

How To Prevent It in the Future

Fungal diseases enjoy damp environments with minimal airflow. You likely noticed the fungal rust on the leaves nearest the ground and hidden from the sun. To prevent the disease from returning, you should make sure the bottom leaves of your hosta have proper ventilation from now on.

Another thing to do is ensure that when you water the plant, the water is hitting the soil, not the leaves. If the leaves are frequently wet, fungal rust will be able to gain a foothold once more. Additionally, keep your hosta away from damp and humid conditions.

Option Two: Leaf Spot Infection

What It Looks Like

Another common disorder that can affect your hostas is Leaf Spot Infection. These spots can appear and grow to any size but will be characterized by a dark brown, almost black-red color. They can also disintegrate the part of the leaf they inhabit, leaving behind small or large holes in your hosta’s leaves. This infection is often caused by bacteria or viruses that attack the plant.

What Causes It

Leaf Spot Infections thrive in damp and outright wet conditions, much like fungal diseases. If your hosta has seen a lot of rain or excess watering, it may be at risk for this type of bacterial infection. Thankfully, these infections are not likely to kill off your plant entirely – they will simply make the plant’s leaves less appealing to the eye.

How To Treat It

Unfortunately, you will not be able to treat a leaf infection like this as quickly as you treat fungal diseases. You will either need to invest in a fungicide with a sulfur or copper base or make your own fungicide made of baking soda and garlic.

Whichever substance you use, apply the mixture as a spray every week until most of the spots fade away. You will likely not be able to rid the hosta of every spot, but you should be able to stop the spread of the infection.

How To Prevent It in the Future

As we discussed in the section about fungal disease, wet environments should be avoided to stop the return of Leaf Spot infections. Ensure your hosta is watered in the morning so it has the day to dry out.

If you notice that other hostas or plants in your garden are infected with Leaf Spot, try to quarantine them from the rest of the plants so the disease will eventually dissipate.

Option Three: Pest Infestation

What It Looks Like

Most pest infestations are easy to identify because the bugs are large enough to see. However, with pests that cause a rust-like spot or wilting, you may be dealing with a much harder-to-see blight: spider mites. Spider mites often fly under the radar until the plant starts suffering, and by then, the infestation is well underway.

What Causes It

If you use an insecticide in your garden, you may have killed off the predators of spider mites. Many insects, including ladybugs, are not bad for your plants and even feed on the smaller pests that eat your plants.

You cannot always predict when spider mites will attack, but if your garden is entirely insect-free, that is likely one of the factors. If you like in a hot or temperate climate like Georgia or Tennessee, you will be no stranger to bugs and will have to adjust accordingly.

How To Treat It

Spider mites can be tricky to eradicate. The first thing you should try in your quest to destroy spider mites is spraying your hosta with a mighty stream of water twice a month. This spraying will hopefully throw the spider mites from the plant and encourage them to find lodging elsewhere.

If water spray does not eliminate the problem, you will need to purchase a miticide (NOT an insecticide). Spray the miticide on the plants as directed to end the mites. It is also wise to remove the leaves most affected by the mites and dispose of them in the garbage; the infected leaves are likely home to more mite eggs.

How To Prevent It in the Future

If spider mites are a consistent problem in your yard, you may want to invest in ladybugs. Ladybugs love to feast on spider mites, and if you place them directly on the plant near a spider mite infection, they will know what to do. Ladybugs will not harm or eat your plants, and you should try to buy ladybug-friendly insecticides if you want to keep other bugs away.

Option Four: Lack of Nutrients

What It Looks Like

If the leaves of your hosta are slowly wilting or turning brown in places, it could be due to a lack of nutrients in the soil. Lack of nutrients is not the most likely reason for your plant’s ailment, but it is possible.

Hostas need frequent fertilization, especially in drier seasons when watering often washes the soil clean. Suppose your hosta is looking generally unhealthy and none of the other signs of fungal disease or infections or mites are present. In that case, you should consider lack of nutrients as a possible culprit.

What Causes It

Several things can cause a lack of nutrients in your plant, but the primary one is poor fertilization. You ought to fertilize your hosta every two to three weeks and even more often when your hosta receives extra water because of heat or dryness (often experienced in desert states like Arizona).

Plants need a good amount of magnesium and calcium, vitamins that need to be provided by the soil and not by photosynthesis.

NOTE: If you are fertilizing your hosta at the recommended intervals, but it still looks unhealthy, overfertilization could also be the offender. If your plant does not improve or worsens with more fertilization, try taking a break from it and simply adding water for a month.

How To Treat It

A lack of nutrients is a simple thing to fix manually. Just increase the amount or frequency of fertilization and watch your plants strengthen in health and happiness!

If you do not have the time to fertilize more often, you can try lessening the amount of water you are giving your hosta. Less water washing through the soil means the nutrients can stay in and benefit the plant for longer.

How To Prevent It in the Future

When you know that your plant needs more fertilizing, you should be able to easily adjust your routine to fit your plant’s needs. You can also invest in different types of magnesium and calcium-rich fertilizer that agree with your hosta. If your hosta is prone to nutrient deficiency, you can also switch the soil surrounding it to a better fit.

Abiqua Moonbeam Hosta

In Conclusion

Spots and disease are common occurrences in plants, even the resilient hosta. Do not be too discouraged that your plant fell victim to common garden concerns: with the knowledge about plant health you have just gained, you are in a better position to look after not just your hosta but the rest of your garden!

Healthy plants will not easily give in to disease, so once your hosta is cured of its problems, be sure to revisit your gardening techniques and give your hostas the best care possible!

You may also like: