Many plant growers are fond of Mint herbs for their distinctive scent and the health benefits.
Mint leaves erupt in pairs from each side of the stems. They have ovate shaped, and you can find tiny hair coats on them.
Though they are delicious, they are not immune to diseases. For example, you may be alarmed by white spots on your precious Mint leaves.
What’s the Reason for White Spots on Mint Leaves?
White spots on Mint leaves appear when bugs or pests attack them. These could be spider mites, thrips, or other plant bugs. Your Mint plant could also be affected by fungus. In such cases, the leaves will have white powdery mildew on their surface.
Are White Spots on Mint Leaves Easily Identifiable?
Whether you can detect the spots at first glance or not depends on the reason behind those spots. Let’s assume spider mites may have caused them. I find their spots relatively easier to identify.
But recognizing the powdery mildew can be more difficult. Mint leaves are already dark in color, and you may ignore the mildew as dust.
You should also note that not all white spots on Mint leaves are born equal. Some of them would look like tiny holes clustered together. Others may be confined to the edges or have large spaces in between.
I’d suggest examining your Mint with a hand glass to confirm what they look like.
What Does the Appearance of White Spots Say About Them?
Knowing more about the appearance of the different white spots will help you find your Mint’s root problem. Here is how you can find out what’s wrong.
Your Mint leaves may have a fine, white dust. It can look like someone sprinkled flour on the leaves’ surface. However, if you touch it, it won’t brush off as the floor does.
These spots are circular, and most plenty of them appear on the upper leaf surface. They are not all bundled together, and you can see spaces in between. This powdery mildew happens when fungus decides to live on your Mint leaves.
Lots of Tiny White Spots
In some cases, you can find that your Mint leaves have tiny white spots. Such white spots happen when spider mites attack your Mint leaves.
These bugs love to hide on the underside of the leaves. So, if you check the lower veins of your Mint leaves, you can find lots of mites. They will be easy to identify because of their numbers.
What you might mistake for white spots can be silver patches. These also look like streaks of white or irregular dotting on Mint leaves. Thrips are responsible for these patches.
The spots they leave may also have some yellow in the center.
Why Do White Spots Occur on Mint Leaves?
Over the years, I’ve realized that pests and fungus are widespread in Mint leaves. So, here are the details for each problem.
Powdery mildew appears when a biotrophic fungus decides to feed off your Mint leaves. These fungi cannot survive without a host. They love attacking healthy-looking plants for the same reason.
If they land on your Mint leaves, they will start to germinate through spores. Since they are tiny, you may not notice.
The fungus can easily pierce Mint leaves as they aren’t very thick. It lets them steal nutrients from the epidermal cells that cover your Mint leaves.
Soon, fungus multiplies and forms new spores and filaments. The technical term for these is “conidiophores.” So, what you view as powdery mildew are the fungus spores.
These are pesky little bugs that look like spiders. They have a waxy abdomen and eight legs that they use to crawl everywhere. Your Mint plants are safe from these in the winter. Unfortunately, spider mites thrive in warmer months.
You may want to check the temperature and the humidity to confirm spider mites. Your plants may be in a dry area with a temperature higher than 85°F. In such conditions, it is very likely to suffer from spider mites.
Female spider mites actively breed on the underside of Mint leaves. They also enjoy sucking the leaf sap. Besides white dots and holes, these bugs also make webs. You can identify the web even before you see the mites.
Thrips are small insects that enjoy dining on delicious Mint leaves. They can be translucent white, yellow, or other colors. The worst part is that thrips also promote virus growth on Mint leaves.
They will lay eggs on Mint leaf tissue and suck the leaf sap. It means the nutrients that your Mint needs will provide energy to these insects instead.
Due to thrips, your dark-green Mint leaves can have silver streaks and patches. Sometimes, when my leaves suffer from thrips, I find their edges turning bronze. It would be best to beware of other signs along with white/silver spots.
What Can You Do About the White Spots?
You have probably identified the cause by now. I also have some tips on how you can deal with the white spots and their cause.
Maintain Proper Plant Care
Using foreign chemicals can stress your plant. To avoid this, place your Mint in a region that it likes. For example, my Mint plant stays happy next to my sunny window. You can also place yours outdoors in the shade.
It’d be wise to isolate sick Mint from other plants. Some of these pests, like thrips, rapidly transfer to plants that are near-by. When you separate your Mint, remember to space out the leaves with white spots.
It creates passages for air circulation, and you can easily mist the leaves this way.
Use Home Remedies for Powdery Mildew
If your Mint leaves have powdery mildew, you want to make a liquid that will drive the fungus away.
You don’t have to get expensive chemicals for it. These materials would be available in your kitchen. You can use mouthwash, baking soda, or vinegar. Mix a small quantity of it in three portions of water, and then spray it on your Mint leaves.
Sometimes, I reuse empty spray bottles to store my liquid. So, you can also do the same with clean water bottles or other empty containers.
However, my favorite solution for mildew on Mint is applying neem oil. It works like magic.
Use Water Hose or Insecticides
For killing thrips or spider mites, you should try the water hose method. It means blasting off a water stream where you see the pests. However, Mint leaves are delicate, and you want to make sure you don’t harm them in the process.
Alternately, you can also turn to insecticidal soaps. Neem oil is also an equally good pesticide for spider mites and thrips. It is non-toxic to plants, humans, and pets alike. Once you have the oil, you can evenly spray it or use a cloth to spread it.
I find a microfiber cloth very useful here. If you are applying the oil by hand, make sure you don’t pull or twist the Mint leaves. Doing it every week can be very helpful in getting rid of the white spots.
Consider Getting Rid of the Mint Plant
Perhaps you tried everything for curing Mint leaves, but the spots don’t seem to go away. If so, it may be time to throw out the entire Mint plant.
It will save the rest of your houseplants from getting viruses, fungal infections, or pests like the Mint had. If you are fond of Mint plants, you can grow a new one and make sure the new specimen doesn’t catch diseases.
Frequently Asked Questions About White Spots on Mint Leaves
Why do the white spots on my Mint leaves keep increasing?
It means that the pests or fungus are breeding on your Mint leaves. Your Mint needs urgent care. Otherwise, it will decay.
Can I eat Mint leaves that have white spots?
If you suspect that your Mint has powdery mildew from fungus, you’ll be better off if you avoid eating it.
Marcel runs the place around here. He has a deep passion for houseplants & gardening and is constantly on the lookout for yet another special plant to add to his arsenal of houseplants, succulents & cacti.
Marcel is also the founder of Iseli International Commerce, a sole proprietorship company that publishes a variety of websites and online magazines.