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Bacterial Leaf Spot On Monstera (Causes and Solutions)

What should you do if you notice nasty spots speckling your Monstera’s leaves? I find it very upsetting when the leaves of my Monstera begin to look sad, sick, and diseased, rather than the bright green expanse they used to be.

Bacterial infection is one of the most challenging causes of spotting to treat. In addition, it can be challenging to remove with the same methods as with fungal spots. But, not to worry; a little effort can get it under control again.

What Causes Bacterial Leaf Spot on Monstera?

A variety of pathogenic bacteria cause bacterial leaf spots. These germs occur naturally and are dormant in the soil.

Spots in Monstera plants are caused by various individual species of bacteria. Bacteria in the Xanthomonas or Pseudomonas families are particularly bothersome, lying dormant in soils and contaminated water until they find a vulnerable victim.

A leaf spot on your Monstera indicates a problem with your care program for an indoor gardener.

A healthy plant that is well watered and kept at the appropriate light level and temperature is usually strong enough to withstand bacterial infection.

A Monstera that has been overwatered is in a dark corner or is in an area that is too cold or hot is more likely to become infected. Poor humidity is also a factor, especially if ventilation is inadequate.

And if you have a sick Monstera in your collection, it’s a good idea to get rid of it. Regardless of the cause, an ill plant must be quarantined before it can infect the rest of your indoor jungle.

Symptoms of Monstera Bacterial Leaf Spot

 Bacterial Leaf Spots on Monstera Leaf
Bacterial Leaf Spots on Monstera Leaf

Take a close look at the leaves to see if your Monstera fights bacterial leaf spots. Examine the surface of the leaf, the undersides, and the stems. The following are symptoms of a bacterial leaf spot infection:

  • Areas on the surface and bottom of the leaf
  • Yellow, black or brown spots
  • Dark spots that dry and flake, revealing dead leaves underneath
  • Spots that ooze sap
  • Brown or black spots featuring a ‘halo’ of pale tissue

Slow growth, new leaves that emerge blackened, browned, or distorted, and generally poor condition are also things to look for.

How will you tell the difference between a Fungal leaf spot and a Bacterial leaf spot?

It’s surprisingly difficult to distinguish between a fungal leaf spot and a bacterial leaf spot. They have similar symptoms and, in many cases, the exact causes.

The most notable distinction is that fungal spots occasionally produce spores. Fungi reproduce by dispersing spores from plant to plant.

Fungal infection is indicated by dusty deposits or powdery substances at the heart of the spot that resembles glitter or flakes of grime.

Temperature and humidity conditions favor the growth of fungi, making them more susceptible to fungal infections.

In another article, I go into greater detail about fungal infections and how they cause brown leaf spots on Monstera.

But, regardless of who is to blame, the outcome is the same. Without treatment, the Monstera will continue to deteriorate and eventually die.

How Do You Treat Bacterial Leaf Spots on Monstera

Step 1: Quarantine

Quarantine is the first and most crucial step in any disease treatment. The bacterial disease spreads slowly and insidiously.

By the time spots appear, the Monstera is thoroughly infected and at risk of infecting your other plants as well.

Move your infected Monstera to a different room as soon as possible. Having a shady porch or balcony where you can quarantine plants is an excellent option if you have a plant hospital of your own.

Step 2: Assess the Severity of Damage

Second, determine the severity of the infection. Finally, thoroughly examine the leaves, inspecting the surface and the underside.

Bacterial spotting can also manifest as wilted, sad-looking new leaves, so check them as well.

Step 3: Fixing Bacterial Leaf Spot on Monstera

For Mild Infections

You can safely remove the infected leaves from your plant if only a few small spots are infected. Snip the diseased leaf close to the vine with clean shears.

Put the infected leaf in your regular garbage. It’s not a good idea to compost a diseased Monstera leaf because it will contaminate the compost and risk the spread of the disease.

For Severe Infections

If you’re seeing a lot of spotting and most, if not all, of your new growth, is struggling, it’s time to bring in the big guns.

Your best line of defense is broad-spectrum plant medicine. Use a spray or soil drench containing these antibacterial and antifungal compounds to keep your Monstera healthy.

They’ll also stay inquisitive fungi from attacking your poor Monstera while it’s in distress.

When applying plant sprays to your sick Monstera, exercise caution. Wear suitable gloves to protect your hands. Move the plant to a well-ventilated area or entirely outside when using treatments.

Finally, always read the instructions thoroughly and dilute according to the manufacturer’s recommendations.

A poorly diluted treatment can wreak even more havoc on an already vulnerable plant. (Check out the prices on Amazon here)

Tips for all Infections:

  • Make sure to sterilize your shears both before and after you use them. Bacteria aren’t picky, and they’ll happily live on your tools, waiting to infect the next plant you prune.
  • Keep the sick plant in quarantine and keep an eye out for any changes. It’s safe to return to your collection once it produces clean leaves and regains its vigor.

How to Prevent Bacterial Leaf Spot in Monstera

After you’ve dealt with your outbreak, it’s time to work on preventing your Monstera from becoming ill in the first place. Fortunately, this is not as difficult as it appears.

  • Only water your Monstera when the top two inches of its growing medium have dried. Dry spells create a hostile environment in the ever-increasing medium, preventing disease-causing bacteria from establishing a foothold.
  • Maintain proper ventilation and humidity levels for your Monstera. They’re pretty tolerant of low humidity, but aiming for 50-60% humidity will help give your dramatic darling the proper pathogen protection.
  • Maintain good hygiene. Water only with clean, freshwater, and repot with new soil. Maintain the cleanliness of your tools as well.

It’s not difficult to protect and nurture the Monstera’s lush geometric leaves with a thoughtful care regimen.

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