6 Most Common Viburnum Diseases and How to Treat Them
Justice is currently studying engineering and has a passion for DIY projects and gardening.
This is a Viburnum davidii plant.
What are viburnum plants?
Viburnum plants are popular in yards and gardens, especially in spring when they are in bloom. Unfortunately, they are prone to certain diseases that can affect their health and appearance over time.
These diseases don’t always visibly affect viburnum plants, so it’s important to know how to spot them so you can start treating them early.
This article covers some of the most common viburnum diseases and how to treat them, along with additional viburnum care tips so you can keep your plants healthy year after year.
1. Armillaria root rot
One of the most common diseases affecting viburnum is armillaria root rot. This disease is caused by a fungus attacking the roots of the plant, causing it to rot and die. The best way to treat this disease is to remove and destroy the affected plant from the soil.
Planting in raised beds can help reduce the spread of the disease because there are fewer opportunities for infected plants to come into contact with healthy ones. It’s also a good idea not to plant new plants in an area where Armillaria root rot has been present for two or more years. There are no chemical treatments for this type of fungal infection, so prevention is key.
It is important to know how this type of fungus spreads: by vegetative propagation.
2. Algae leaf spot
This disease is caused by a type of algae that thrives in moist, shady conditions. Algal leaf spot appears as small, dark spots on the leaves of the plant. If left untreated, the spots will eventually turn brown and cause the leaves to fall off.
To treat algae leaf spots, remove infested leaves and dispose of properly. Cut back overgrown branches to increase air circulation. Spray with fungicide every 10-14 days until no new signs of algal leaf spot appear.
The fungicide must be reapplied after rainfall or heavy watering. There are also preventive treatments for algae leaf spot that can be used before planting your viburnum, such as: B. organic soil amendments such as compost tea and biological fertilizers. These products help suppress the growth of bacteria and fungi that can cause disease.
For a more natural option, mist plants with garlic extract once a month or use copper-based sprays. These substances inhibit fungal growth without affecting the overall health of the viburnum.
It is important to note that all of these methods should be used only in the absence of visible signs of disease. Once symptoms appear, they should not be treated as this can make the problem worse.
Also, be sure to give the viburnum plenty of room to grow away from surrounding trees and shrubs. With proper care, snowballs can live up to 30 years!
This pathogen is called Cephaleuros virescens
3. Powdery mildew
This powdery mildew appears as a white or gray powdery growth on the leaves and stems of the plant. Powdery mildew can weaken the plant and make it more susceptible to other diseases, so it’s important to treat it as soon as possible.
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There are a few different ways to treat powdery mildew, including chemical fungicides, horticultural oils, and home-made solutions.
The most common treatments for powdery mildew involve either using a good quality liquid horticultural oil (like Alamo), using your favorite commercial spray fungicide with an oil carrier (like chlorothalonil), or spraying your plants with water that you’ve dissolved bicarbonate soda in one tablespoon per gallon.
All three methods work well, but they take time to show their effects. If left untreated, powdery mildew will eventually kill viburnum plants because it weakens them and gives other pests a chance to attack them.
My favorite way to stop powdery mildew is to apply something like garden spray or almond oil to the surface of the plant before symptoms show.
Another option is to use a natural product like neem oil or coconut oil diluted with water that has been acidified with lemon juice. All of these are highly effective against powdery mildew, but only if applied early enough to prevent it from forming in the first place.
This is a powdery mildew.
4. Leaf fungus spot
Fungal leaf spot is one of the most common diseases affecting viburnum. These spots are usually circular or angular and can range in color from pale yellow to dark brown. If left untreated, these spots can eventually lead to leaf drop.
To treat this disease, remove affected leaves and dispose of them properly. You can also spray the plant with a fungicide containing copper or mancozeb. Repeat the process as needed for best results.
This disease also has some preventive measures you can take:
- If necessary, cut off older stems.
- It is also important to water your plant well.
- Soil that is too dry can increase susceptibility to infection.
- For better drainage, be careful not to overwater it.
5. Downy mildew
This disease is characterized by fuzzy, off-white growths on the leaves of affected plants. Downy mildew usually appears in late spring or early summer and can spread quickly if left untreated.
Luckily, there are a few things you can do to treat this disease and prevent it from spreading.
- First, make sure to remove any affected leaves from the plant as soon as you see them.
- Then mix a solution of baking soda and water until it reaches the consistency of white glue.
- Finally, apply the mixture generously to all affected parts of the plant with a brush or spray bottle.
- Within two weeks the downy mildew should be gone!
Downy mildew attacks snowballs and their species on average at least once a year. However, you can minimize the effects by watering your plants well during dry periods. You should also try to plant Viburnum in full sun if possible, as they prefer direct sunlight over shady areas.
Finally, you can get rid of some disease-carrying mites by washing infected branches thoroughly in lukewarm water every two weeks.
A pathogen that causes downy mildew on cucurbits spreads its spores between fields on the wind.
6. Botryosphaeric Cancer
The disease causes cankers or dead areas on the stems of the plant. The crabs are often dark in color and may ooze juice. The disease can spread quickly and kill a viburnum plant if left untreated. Treatment of this disease includes cutting out affected branches and stems and destroying them. Additionally, fungicides can be used to prevent the spread of the disease.
Wound cancer is not common but can be found in snowballs. To identify wound cancer, look for gray streaks growing in the branches of your viburnum. Over time, these gray streaks become more noticeable, turning into dark areas of bark that ooze sap when you touch them.
Wound cancer can eventually spread to your plant; However, the spread is slowed by cutting out affected parts of a snowball with secateurs or a knife. Left untreated, wound cancer infection will lead to the death of the viburnum tree.
Take care of your viburnums
There are a few things you can do to keep your viburnums healthy and prevent disease.
- Make sure you plant them in a spot that gets plenty of sunlight and has well-drained soil.
- Water them regularly, but don’t overdo it — too much water can actually lead to fungal diseases. Third, add a layer of mulch around the base of the plant to retain moisture.
- Prune dead or diseased branches as soon as you see them.
- Finally, you should treat your snowballs with fungicides at least once a year during the hottest months.
Remember that these steps will not only keep them healthy now, but will also help protect them from potential problems in the future. To identify the most common types of viburnum disease, you need to know one thing: they are all related!
Unfortunately, there is no way to completely avoid all types of diseases, as many strains share some common traits. The good news is that different species tend to appear together on plants.
To the best of the author’s knowledge, this content is correct and truthful and does not replace formal and individual advice from a qualified professional.
© 2022 Justice Ndlovu