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Roseamore
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Is this a fungus affecting my mints?

Hi Guys,

I have been observing brown and yellow spots on my mint leaves. One of my mints is very thick and I noticed the spots first on leaves which were not getting any sun and as a result were almost permanently damp. I cut back the plant so that more of it would be exposed to sun but that did not make a difference.

Recently I noticed that almost all of my mint plants have these spots especially on their lower leaves. It must be noted that it has been rain almost everyday and every night for at least the last week. As a result the plants are moist almost indefinitely.

From my research on line it seems that I have a fungal infestation but I'm not sure. Please see the attached pictures.

Please let me know what you think. If it is an infection what is the best way to treat it?

Thanks in advance.

Roseamore
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imafan26
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Re: Is this a fungus affecting my mints?

It looks like mint anthracnose, aka leopard spots. It is a fungal disease. You will need to pick off and destroy the bad leaves, let the plant dry out. The spores probably spread to the other plants. In severe infections, it is very difficult to control. If you have any good parts left, cut the plant back and repot iwith new soil and a new pot using the root runners make sure your pots are well drained. You can sterilize the old pot by cleaning it well and then soaking the pot in a bucket with water and bleach. Let it sit for 24-72 hours.
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Roseamore
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Re: Is this a fungus affecting my mints?

Hi Imafan26,

Thank you for verifying that it is a fugus and for the advice. I will deal with the plants that are in pots tomorrow. However, the plant which is pictured is planted in the ground so repotting is not an option. Is there anything I can apply it to?

Thanks again.

Roseamore
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imafan26
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Re: Is this a fungus affecting my mints?

There are not a lot of things registered for herbs. The fungal disease is listed as a minor problem of mint usually caused by planting in waterlogged conditions. Mint can be planted in mucky soil since it is shallow rooted and tolerates that, but it is better in well drained soils.

You could regenerate the mint patch. Cut out the worst parts of the plant and let the patch dry up. Most of the time the mint recovers on its own. If the spot is low, I would add some sand on top of the mint a little at a time to raise the level. I don't use compost or mulch in very wet conditions because it just helps hold on to water. Honestly, mint in the ground is pretty hard to kill. I have put compost over it and it comes through. The soil is heavy and constantly moist, but the mint stays shallow and it is in full sun so the top where the leaves are are pretty dry.
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rainbowgardener
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Re: Is this a fungus affecting my mints?

Mint is prone to blackened leaf edges and spots, but usually it is really only a cosmetic issue. The plant is quite hardy and isn't very slowed down by it. If you don't like how it looks, just cut it back. Make sure there is good drainage and air circulation to prevent the problem from coming back with it.
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Re: Is this a fungus affecting my mints?

Along with suggestions above, there is a copper spray for fungus. I got some a couple of yrs ago when there was some bothersome fungus. Last season used some on the tarragon that was getting the cooties. Mine came in a spray container like a windex container. I try not to use it, but it is relatively safe and used by the organic farmers.
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Roseamore
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Re: Is this a fungus affecting my mints?

Dear Everyone,

Thank you for your advice and information. I cut back and repotted the mints today and I destroyed the one that was first infected with the fungus.

I must confess that I was a bit afraid to cut back but then I saw a video on line where a guy cut off all the leaves and stems and then repotted a couple of the root runners.

I'll monitor them and hopefully all will be well.

Bearing in mind what Rainbowgardener said, I'll leave the one which is in the ground and see how that goes.

Thanks again.

Roseamore
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applestar
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Re: Is this a fungus affecting my mints?

If milk allergy is not a concern, I would spray with milk solution just because it won't do any harm (as far as I have experienced) and may help. When I do spray with milk solution, I spray everything that gets fungal issues including mint and magnolia. Milk solution and dilute AACT are the only things except water that I spray indiscriminately.

If you can make a batch of AACT (actively aerated compost tea -- there is a sticky in the compost forum) that will help to invigorate the plant and help to fight off the disease.
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Roseamore
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Re: Is this a fungus affecting my mints?

I'm not sure where I would find AACT on this island; I will ask around (looked it up and I am sure that at this point I would not be able to make it).

We are not allergic to milk but we don't drink it. However, I am presuming that by the time we are ready to use the leaves from the plant the milk would have been washed off or would have evaporated.

Thanks Applestar

Roseamore
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rainbowgardener
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Re: Is this a fungus affecting my mints?

You don't "find" AACT; you make it. Once it is made, it needs to be used right away and does not keep. I resisted making it for years, because it sounded hard, but when I finally did try it was very easy. All you need is a bucket, an aquarium pump with airstone (that you can buy cheap in any pet store), and some fresh garden compost. Put compost, water, a bit of molasses in the bucket with the pump to aerate it and let it sit 36 -48 hrs. Voila, AACT!
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Roseamore
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Re: Is this a fungus affecting my mints?

You are right Rainbowgardener, it does sound hard in some of the articles I've read online but you have made it seem almost doable :)

I will not try it just yet but some time in the future.

Thanks.

Roseamore
Patience and plants grow side-by-side.... The art of gardening cultivates them well.

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