Ever had your mint plant’s leaves go white and wondered what gives? If you’ve been babying your mint and see this change, it might make you think your green thumb’s gone rusty.
There’s a handful of reasons why mint leaves might be sporting a white coat. Often, it’s down to diseases like powdery mildew or physiological disorders. Let’s break it down step by step.
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What Are The Symptoms of Powdery Mildew?
What seems like a harmless white film is actually the work of parasitic powdery mildew fungi. They start looking like they’ve been dusted with flour – that’s the mold setting up shop.
These sneaky critters burrow into plant cells and suck the life right out of them. Within a few days of mildew showing up, the plant’s lower leaves are yellow, droop, and start to crumble.
Those are mold spores ready to hitch a ride on the wind and infect your other mint plants. Once they latch on, even the healthiest leaves turn white or have white powders on leaves.
The sneaky fungi behind powdery mildew are tough cookies. They can hibernate in the soil, waiting to pounce the next year. So keep your eyes peeled.
When’s The Prime Time for Powdery Mildew?
Between May and October. If you notice your mint leaves whitening during these months, it’s time to sound the alarm.
Powdery mildew symptoms start as little white spots on your leaves. As it worsens, the mold blankets the leaf until completely covered.
Look a bit closer and see sores where the fungus has dug in. The plant tissue looks like it’s had a rough day. The plant’s definitely feeling the heat as these fungi drain its nutrients.
And if that’s not enough, the white layer on the leaves puts the brakes on photosynthesis, sending the plant into a tailspin. You gotta nip powdery mildew in the bud with whatever you’ve got, or the plant’s a goner.
What Conditions Are A Breeding Ground for Powdery Mildew?
It likes dry spells and minimal rain, so be careful when you hit a string of cloudy, low-humidity days.
Also, if you’re heavy-handed with the fertilizer and end up with a bushy plant, or if your plants are crammed together, blocking sunlight and airflow, you’re basically rolling out the red carpet for powdery mildew.
Powdery mildew fungi are a dime a dozen in the soil but don’t always bear their fangs. On a sunny day, when your plant’s getting plenty of water and food, these fungi don’t have a prayer. They only start to cling and grow if:
- On top of these conditions, spores that have been woken up can hitch onto mint.
- They can float over from infected trees or plants, sneak in through your watering can, or even hitch a ride on your hands if you’ve handled an infected plant before touching a healthy one.
Battling Powdery Mildew: Healing Sprays and Watering
To kick powdery mildew to the curb, here’s what you gotta do:
- Pluck off infected (yellow, wilted) mint leaves. The more infected branches and leaves you get rid of, the better your plant’s chances of bouncing back.
- Swap out the top layer of soil in the pot, container, or flower bed – it’s a hotbed for fungal mycelium.
- Give your plant a good spray and water with one of the fungal solutions. Aim to get all the leaves and shoots good and wet when spraying, like after a spring shower. A more effective method: dunk the whole bush in a basin filled with the fungicide solution. This also saturates the soil via spraying or watering. Don’t forget to treat the pot walls and trays, too.
For the treatment of fungal diseases. Here are the fungicides I recommend:
| Name of The Fungicide | Amount | Amount of Water |
| Bonide 811 Copper 4E Fungicide | 1-4 tablespoons (.05-2.0 fl oz) | 1 gallon of water |
| Garden Safe Brand Fungicide3 | 2 tablespoons (1 fl oz) | 1 gallon of water |
| Southern Ag – Liquid Copper Fungicide | 3-4 tablespoons | 1 gallon of water |
Powdery Mildew on Mint: Homemade Natural Remedies
Let’s be clear upfront: homemade remedies for powdery mildew work best as preventative measures or in the early stages of the disease.
If the destructive process has been at play for a while, say, over 5-7 days, it’s too late for this approach. You might be able to hit pause on the disease’s development, but it won’t wipe it out completely.
Here’s how you whip up the most effective homemade remedies for powdery mildew:
1- From washing soda and soap
Dissolve 0.88 oz (25 g) of washing soda in 1.32 gallons (5 liters) of hot water, then add 0.18 oz (5 g) of liquid soap.
Spray the plants and the top layer of soil with the cooled solution 2-3 times, with a week’s gap.
2- From baking soda and soap
In 1 gallon (4 liters) of water, dissolve 1 tablespoon of baking soda and 1/2 teaspoon of liquid soap. Spray 2-3 times, with a 6-7 day interval.
3- Potassium permanganate solution
Dissolve 0.09 oz (2.5 g) of potassium permanganate in 2.64 gallons (10 liters) of water. Use 2-3 times, with a 5-day gap.
4- Whey solution
Dilute whey with water 1:10. The resulting solution forms a film on leaves and stems, making breathing tough for the fungus.
At the same time, the plant gets extra nourishment from beneficial substances and perks up, improving its looks. Apply the whey solution in dry weather at least 3 times, with a 3-day gap.
5- Field Horsetail Decoction
Take 3.5 ounces (100 grams) of fresh field horsetail, cover it with 1.06 quarts (1 liter) of water, and let it sit for a day. Pop it on the stove and let it simmer for 1-2 hours.
Strain it, let it cool, dilute it with water at a 1:5 concentration, and spray your bushes. You can store the concentrate in a cool, dark place for up to a week.
Regular horsetail sprays can help prevent powdery mildew in the spring and summer. To fight an existing infection (in the early stages), 3-4 sprays every 5 days should do the trick.
6- Mustard Solution
In 2.64 gallons (10 liters) of hot water, mix in 1-2 tablespoons of dry mustard. The cooled solution is excellent for both spraying and watering.
7- Ash + Soap
In 2.64 gallons (10 liters) of warm water (86-104°F/30-40°C), mix in 2.2 pounds (1 kg) of ash. Let the solution sit for 3-7 days, stirring regularly.
Then, drain the liquid (leaving the ash sediment) into a clean bucket, add a little liquid soap, fill a sprayer, and start treating your plants. Spray your plants daily or every other day for a total of three times.
For the ash that settled at the bottom of the first bucket, add 2.64 gallons (10 liters) of water, mix it, and use it for watering.
8- Rotted Manure Infusion (preferably cow)
Fill a container with rotted manure and water at a 1:3 ratio, and let it sit for three days. Then, dilute the concentrate with equal water and spray your bushes.
9- Garlic Infusion
Take 1 ounce (25 grams) of crushed garlic, cover it with 1.06 quarts (1 liter) of water, and let it sit for a day. Strain it, and use the infusion to spray your mint.
Preventing Powdery Mildew
Before powdery mildew turns your mint leaves white and withers them away, there are preventative measures you can take. Let’s get started!
1- Spacing Mint Plants
To ensure proper sunlight and airflow to the leaves and stems of your mint, it’s important to plant them with plenty of space in between. Let’s leave about 1 foot (30cm) of space between each mint plant.
2- Careful with Mint Fertilization
Powdery mildew often strikes when there’s too much nitrogen fertilizer. Even if you’re eager to grow your mint big and strong, don’t apply too much nitrogen fertilizer immediately.
3 -Disposing of Infected Leaves and Plants
Powdery mildew starts on the leaves of your mint and can spread to the entire plant. Dispose of affected leaves and plants as soon as you notice them to protect the rest of your crop.
Make sure to carry them out of your garden to avoid scattering the white powder onto healthy leaves.
Key Takeaways
- Powdery Mildew Symptoms and Conditions: Powdery mildew, a sneaky fungus, makes your mint leaves look like they’ve been in a flour fight. It’s hunky-dory when there’s ample rain, but watch out when you hit a dry spell! Cramped plants lacking sunlight, airflow, and too much fertilizer are a red carpet invitation for this fungus.
- An Ounce of Prevention: Keeping powdery mildew at bay is a cinch! Plant your mint with elbow room—about a foot apart. Don’t go hog wild with the fertilizer, especially the nitrogen kind. And if you spot any sickly-looking plants or leaves, nip them in the bud to keep the rest of your mint safe.
- Healing Sprays and H2O: If you’re already dealing with powdery mildew, don’t sweat it! Pluck off the infected parts, swap out the top layer of soil, and give your mint a good spritz with a fungicide.
- DIY Remedies: If you’re feeling crafty, whip up a homemade remedy to kick powdery mildew to the curb or stop it in its tracks. Your kitchen cabinet is chock-full of potential treatments, from washing soda and soap, baking soda and soap, to more exotic solutions like field horsetail decoction or a garlic infusion.
- Keeping an Eagle Eye: Here’s the rub—the fungi that cause powdery mildew to play a long game. They can snooze in your soil, ready to return to life next year. So, keep your peepers peeled! Quick action at the first sign of trouble can save your mint plants a world of hurt.