Staff Answer
May 17, 2022 - 07:06 AM
The black speckles are usually benign but, if they're growing in size, some intervention may be needed.
The first steps should be environmental. Keeping the cactus in as dry of air as possible will slow or even prevent the speckles from growing. Allowing the plant to receive full, natural sunlight will help as well. The natural sunlight has UV radiation in it (the radiation responsible for sunburns) that can slow or kill many topical fungi. Being very careful not to overwater will help as well but, if the black speckles are they only issue, I doubt this is your problem.
If you really want to hammer these speckles, you can try a more active treatment. An over the counter fungicide would work well here but you can also use a dilute solution of hydrogen peroxide and water (roughly a tablespoon of the peroxide per gallon of water). Please note, if your treatment involves some sort of alcohol, keep your cactus out of the direct sun for a few hours after treatment. The alcohol can encourage sunburning.
We would certainly be happy to look at your cactus if you have any additional concerns. You can email us a few clear photos of your cactus to info@mountaincrestgardens.com. If you do send us some pictures, be sure to include the following information:
1) Growing conditions (full sun, part sun, filtered sun, indoors, outdoors, etc.)
2) Soil used for planting
3) Watering schedule
4) Does the container have a hole for drainage?
The first steps should be environmental. Keeping the cactus in as dry of air as possible will slow or even prevent the speckles from growing. Allowing the plant to receive full, natural sunlight will help as well. The natural sunlight has UV radiation in it (the radiation responsible for sunburns) that can slow or kill many topical fungi. Being very careful not to overwater will help as well but, if the black speckles are they only issue, I doubt this is your problem.
If you really want to hammer these speckles, you can try a more active treatment. An over the counter fungicide would work well here but you can also use a dilute solution of hydrogen peroxide and water (roughly a tablespoon of the peroxide per gallon of water). Please note, if your treatment involves some sort of alcohol, keep your cactus out of the direct sun for a few hours after treatment. The alcohol can encourage sunburning.
We would certainly be happy to look at your cactus if you have any additional concerns. You can email us a few clear photos of your cactus to info@mountaincrestgardens.com. If you do send us some pictures, be sure to include the following information:
1) Growing conditions (full sun, part sun, filtered sun, indoors, outdoors, etc.)
2) Soil used for planting
3) Watering schedule
4) Does the container have a hole for drainage?
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