Why are my viburnum leaves turning brown?

Uh Oh, Are Your Viburnum Leaves Turning Brown? Let’s Figure Out Why!

Viburnums! Aren’t they just gorgeous? Those lush leaves, the delicate flowers, and, if you’re lucky, berries that pop with color. But what happens when those beautiful leaves start turning brown? It’s a real buzzkill, I know. Don’t panic, though! Browning leaves are a pretty common problem, and usually, it’s something you can fix. The key is figuring out why it’s happening in the first place. Is it a pesky fungus, some kind of stress, or maybe even unwanted pests? Let’s dive in and get to the bottom of this.

The Usual Suspects: Fungal Diseases

Fungi are often the bad guys when it comes to viburnum woes. There are a few different types that can cause trouble, and each one has its own tell-tale signs.

• Leaf Spot Diseases: These are super common. Think of them like little blemishes popping up on the leaves. You’ll see spots – sometimes round, sometimes a bit jagged – that range from a sickly yellow to a dark, ominous brown. Nasty culprits like Cercospora, Phoma, and Phyllosticta are often to blame. And if you see black, sunken spots? That could be anthracnose, caused by Colletotrichum. These diseases just love warm, humid weather – perfect for spreading.
  • What to do: First things first, get rid of those infected leaves! Don’t let them hang around spreading the funk. Prune back any nearby plants to get some air flowing. If things are really bad, you might need to bring out the big guns – fungicides. Look for ones with ingredients like chlorothalonil, thiophanate-methyl, or mancozeb. Copper fungicides can also do the trick.
• Downy Mildew: This one likes things cool and damp. You’ll notice light green spots on the top of the leaves at first. Then, they’ll spread out into weird, angular shapes. Flip the leaf over, and you might see a fuzzy, grayish-white growth. As it gets worse, the spots turn red and then brown. It’s not a pretty sight.
  • What to do: Airflow is your friend here. Avoid watering from above, which just encourages the fungus. If you need to, use a fungicide specifically for downy mildew.
• Powdery Mildew: You’ve probably seen this one before – it looks like someone sprinkled flour all over your plants. It’s caused by Erysiphe sparsa fungi. Viburnums in shady spots are especially prone to it.
  • What to do: Prune those branches to let the air circulate! And again, avoid getting the leaves wet when you water. Remove any leaves that are already infected. For a bad case, try a horticultural oil.
• Algal Leaf Spot: Okay, this one’s a bit different – it’s caused by algae, not a fungus! It likes moist, shady spots. You’ll see small, pale green spots that turn light brown or reddish-brown. They often look a little raised and velvety.
  • What to do: Get rid of those affected leaves and prune back any overgrown branches. Copper fungicides or garlic extract can help, too.
• Botryosphaeria Canker: This is a sign that your viburnum is stressed out – maybe it’s too dry, or it got injured somehow. You’ll see wilting leaves and branches dying back. Look closely, and you might see tiny, dark brown bumps on the branches.
  • What to do: Prune away those dead branches! Make sure your viburnum is getting enough water, especially when it’s dry.

Bacterial Blight: Another Nasty Disease

Pseudomonas syringae pv viburni causes bacterial blight, primarily affecting leaves and occasionally stems . Spots on leaves initially appear as brown, water-soaked areas . Developing leaves may become deformed if heavily infected . Severe infections can also result in shoot dieback .


* Treatment: Apply fungicides in September and again before fall rains. An additional application may be made as new growth emerges in the spring .

Bugging Out: Pesky Pests

Sometimes, the browning is caused by critters munching on your viburnum.

• Viburnum Leaf Beetle: These guys are major pests. The larvae are the real troublemakers – they skeletonize the leaves, leaving them looking like lace. I’ve seen entire viburnums completely stripped bare by these beetles!
  • What to do: Keep a close eye on your plants and pick off any larvae you see. Prune away any infested twigs. If it’s a full-blown infestation, you might need to use an insecticide.
• Root Weevils: These sneaky pests attack the roots, which can lead to stunted growth and yellowing leaves. If they’re really bad, they can even kill the whole plant.
  • What to do: Insecticide sprays can help with the adults, and you’ll need to treat the soil to get rid of the larvae.
• Spider Mites: These tiny pests suck the life out of leaves, causing them to turn grayish-brown. You might even see fine webbing.
  • What to do: A strong blast of water can knock them off. For bigger problems, try insecticidal soap or horticultural oil.
• Thrips: These little guys cause silvery streaks on the leaves. If there are a lot of them, the leaves and flowers can get all distorted and turn brown.
  • What to do: Insecticidal soap or horticultural oil will take care of them.
• Aphids: These pests feed in clusters at the tips of branches, causing leaf curl .
  • Treatment: Viburnums can be sprayed with insecticidal soap or horticultural oil to control aphids .

It’s Not Always Bugs and Fungus: Environmental Stress

Sometimes, the problem isn’t a disease or a pest – it’s something in the environment.

• Water Woes: Too much or too little water can both cause problems. Overwatering can lead to root rot, while underwatering causes drought stress. It’s a Goldilocks situation!
  • What to do: Get your watering schedule right! The soil should be consistently moist, but not soggy. Mulch can help keep the soil from drying out too quickly.
• Sunburn: Just like us, plants can get sunburned! Too much direct sun, especially in hot weather, can scorch the leaves.
  • What to do: If possible, give your viburnum some shade during the hottest part of the day. Or, if you’re moving it to a sunnier spot, do it gradually.
• Transplant Shock: If you just planted your viburnum, it might be in shock. This can cause wilting and browning leaves.
  • What to do: Water it regularly!
• Nutrient Deficiencies: If the soil isn’t up to par, your viburnum might not be getting the nutrients it needs.
  • What to do: Get a soil test to see what’s missing, and then amend the soil accordingly.
• Winterburn: This happens when the leaves lose moisture during the winter, but the roots can’t replace it because the ground is frozen.
  • What to do: There’s nothing you can do after winterburn occurs to remedy the situation since the damage has been done to foliage. The plants should shed the damaged leaves later this season as they put out new growth .

Prevention is Key!

The best way to deal with browning leaves is to prevent them in the first place. Here’s how:

• Choose the Right Viburnum: Some varieties are more resistant to diseases and pests than others.
• Pick the Perfect Spot: Make sure your viburnum has the right amount of sunlight and well-draining soil.
• Give it Room to Breathe: Good air circulation is essential. Don’t overcrowd your plants!
• Water Wisely: Water deeply, but not too often. And avoid getting the leaves wet.
• Keep an Eye Out: Check your plants regularly for any signs of trouble.
• Clean Up: Rake up and get rid of fallen leaves to prevent diseases from spreading.
• Feed it Right: Give your viburnum the nutrients it needs, based on a soil test.

So, there you have it! Browning viburnum leaves can be a bummer, but with a little detective work and some TLC, you can usually get your plant back on track. Happy gardening!