How to Treat Leaf Spot

What is leaf spot and how can I identify it?

Leaf spot is a common fungal or bacterial infection that plagues houseplants. It causes unwanted brown spotting, sometimes accompanied by a yellow or reddish halo, that can spread like wildfire from leaf to leaf, or even plant to plant. This can occur due to a variety of environmental factors, and unfortunately, is a frequent plant-killer. 

The first sign of infection is usually a grouping of small brown spots. These can sometimes merge together to form larger areas of browning, or can harden into small, reddish-brown spots over the leaf. You may also notice holes forming within the discoloration. This is because the infection eats away at the leaf tissue.

What causes it?

There are multiple ways that leaf spot can be encouraged to appear. Consistently high humidity levels paired with poor air flow and circulation is the most common cause. Another common mistake is splashing water onto leaves during watering or over-misting foliage. Fluctuations in temperature can also threaten the safety of your plants, so try to keep the room at a comfortable, consistent temperature. These acts seem helpful, but if not done carefully, can create the perfect breeding ground for these bacterias and fungi to take form.

Treatment:

1. Prune and remove heavily affected leaves. If there is only one spot or two, skip this and follow the next steps.
2. Provide frequent treatment of neem oil or another fungicide to the foliage. Copper-based fungicides are safe and effective for most plants, but always do your research – copper can be harmful to certain plants. 
3. Avoid getting water onto the leaves as it recovers.
4. Keep the plant  away from other plants temporarily. This will prevent the infection from spreading to the foliage of your other plants.
5. Monitor daily to ensure the infection has stopped spreading.
6. Repeat steps 1-5 until you’re certain the plant has beat the infection.

Prevention: 

To prevent leaf spot from taking out your plants, try these tips and tricks:

1. Provide good air. You can do this by running an air purifier or fan nearby, or by keeping a window slightly open, especially during summers when it gets hot and humid.
2. Avoid misting or splashing. Getting water onto your leaves. While some plants (ferns, air plants, etc) like high humidity and appreciate misting, many others won’t react well to being wet all the time, as this makes them  more prone to infection. 
3. Space out your plants. Give your plants some more breathing room so they aren’t overcrowded and bumping leaves with others. This limits the potential spread of leaf spot from plant to plant.
4. Routine neem treatments. Spraying your plants with neem oil every month as a preventative towards bacterial, fungal, and pest issues will help catch any early start of leaf spot before it spreads beyond control.