As a proud cactus parent, I know how distressing it can be to notice strange spots appearing on your prized succulents. Recently, I noticed some abnormal white dry spots surfacing on a few of my cacti. Naturally, I panicked! Were these innocuous spots or a more sinister sign of disease?
To get to the bottom of this cactus quandary, I did some digging into the potential causes of white spots. What I uncovered provided some fascinating insights into cactus care and reassured me that my spotty spiky friends would be A-okay.
In this article, I’ll share what I learned about the main causes of white dry spots on cacti, along with tips to prevent and treat them. Let’s get to the root of this prickly problem!
What Triggers White Spots on Cacti?
There was agreement among cactus care experts and forum posters that white spots are usually caused by one of three things.
Sun Exposure
Cacti get white spots most often when they get too much sun. We all know that cacti do best in the sun, but too much or sudden light can burn their skin, leaving bleached white spots. This phenomenon is known as sunburn or sunscald.
Cacti sunburn easily for two reasons First, their thick, waxy epidermis acts like a magnifying glass, intensifying the sun’s rays Second, most houseplant cacti originate from deserts where they grow under nurse plants or rocks that filter sunlight.
To avoid sunburn gradually acclimate new cacti to increased light levels. Rotate indoor plants frequently so all sides receive equal sun. Outdoor cacti may need shade cloths to shield them during intense afternoon light.
Overwatering
Another common culprit behind white spots is overwatering. Cacti have adapted to thrive in arid desert environments. Too much moisture can lead to fungal diseases like root rot, which manifest as dry white marks on the outer skin.
Follow a “less is more” watering plan to keep your plants from getting too much water. Wait until the soil is completely dry before watering again. Cut back on watering in winter when plants are dormant. Cacti should be kept in pots with holes in the bottom so that water can drain away.
Pests
Certain insects and bugs can leave white spots or trails on cacti. Mealybugs are fuzzy white parasites that extract nutrients, leaving dots where they feed. Scale insects affix themselves to cacti and secrete white waxy coverings. Spider mites form silky white webs and suck the juices from plants.
Insect infestations often start in hard-to-see nooks of the cactus. Check regularly for any small white critters or spots. Remove pests with tweezers, soap and water, or insecticidal spray. Isolate infected plants to prevent spreading.
Dry Spots Versus Wet Rot on Cacti
When looking at white spots, it’s important to tell the difference between dry marks and signs of wet bacterial rot because they need different treatment. Here’s how to tell the difference:
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Dry spots have a bleached, papery texture. They are flat and harden into scab-like marks over time. The inner flesh beneath is still firm.
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Wet rot spots feel mushy or slimy. They start off translucent then turn brown. The inner tissue is water-soaked and disintegrates easily. Foul odor may accompany rot.
Dry spots can simply be monitored over time. But wet rot requires immediate action to prevent decay spreading. Severely rotted sections should be cut off using sterile shears. Apply fungicide to the wound to prevent infection.
Natural Remedies to Treat White Spots
While white spots rarely seriously harm cacti, you can take steps to improve their appearance and prevent further damage:
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For sunburn – Gradually re-acclimate to proper light levels. Apply aloe vera gel to soothe scorched skin.
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For overwatering – Repot in fresh, dry soil. Sprinkle on cinnamon powder, a natural anti-fungal.
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For pests – Wipe leaves with cotton balls dipped in rubbing alcohol to kill bugs. Use neem oil spray as a natural deterrent.
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For scarring – Consider transplanting damaged sections below soil level to hide marks.
When to Worry About White Spots
In most cases, small white spots are purely superficial and not a major cause for concern. Here are some signs that may indicate a more serious underlying problem requiring prompt attention:
- Spots rapidly spread across multiple cacti.
- Marks are accompanied by soft, oozing rot.
- You notice tiny insects congregating on spots.
- Inner tissue under spots feels mushy and deflated.
- Plant seems weak, wilting or collapsing.
If your cactus displays any of these more troubling symptoms, isolate it from other plants and investigate solutions with a horticulturist. Catching issues early maximizes the chances of recovery.
Cactus Care Tips to Prevent Spots
Prevention is the best cure when it comes to problematic cactus spots. Here are some proactive care tips to keep your succulents happy and spot-free:
- Allow soil to dry between waterings and reduce water in winter.
- Provide strong light but avoid hot afternoon sun.
- Repot in porous cactus soil for drainage.
- Rotate plant to evenly distribute light exposure.
- Check for pests regularly under leaves and spines.
- Clean shears between clippings to prevent bacteria spread.
- Transition indoor cacti outside gradually to avoid sunshock.
- Water at the base, not on leaves, to discourage rot fungi.
Embrace Your Spotted Cactus!
If your beloved cactus does end up developing some cosmetic white spots, don’t despair! Dry spots don’t have to be the end of the world, or even an eyesore. Some people creatively transform sunburnt scars into decorative features by painting them with contrasting colors or inking them into designs. Personally, I’ve come to accept my spotty cacti as they are – quirks and all! Cactus maintenance inevitably involves some minor flaws. Just be sure to keep a close eye on spots to catch any problems before they spiral. With vigilance and care, your prickly pal will continue to thrive spots and all!
Reason 2: Scale Insects
You might have run into scale insects if you’ve noticed tiny, flat bumps on your cactus. They’re sneaky little pests that settle onto plants and look almost like small, natural spots. I’ve seen them in colors ranging from brown to tan, and sometimes even white. At first glance, you might just think they’re part of the cactus. I did the first time I saw them!.
The thing is, as they settle in and start feeding, they can cause the cactus to have yellow or pale spots. And guess what? Like their pesky cousins, the mealybugs leave behind this sticky residue known as honeydew. This can sometimes lead to a black, sooty mold on your beloved cactus. If your cactus is getting sticky or showing odd bumps, it might be time to check for scale insects. Acting early can save a lot of hassle and keep your plant pal in good shape!.
Do you know how we sometimes get sunburned if we’re in the sun too long without protection? Well, cacti can experience something similar! Even though they’re adapted to sunny environments, sudden exposure to intense sunlight, especially after being in the shade for an extended period, can cause sunburn. Most of the time, white or pale spots on the side of the cactus that faces the sun are the first sign. These patches can look bleached and stand out from the plant’s standard color.
The tricky part is that these sunburned spots on cacti don’t heal like ours do. The affected area might become corky or scaly over time. It’s essential to be mindful when moving our prickly friends to sunnier spots or buying a new one in a shaded store. A gradual introduction to sunlight can help prevent these unsightly sunburns and keep your cactus looking its best.
If you’ve noticed weird, white blisters or corky patches on your cactus, it might be dealing with something called edema (pronounced eh-DEE-ma). Edema in cacti happens when they take in more water than they can use, especially when the soil is very wet, and the environment is cool or humid. In simpler terms, it’s like the plant version of water retention. The cells in the cactus soak up too much water, swell up, and then burst. Once they burst, they leave behind those rough or corky patches we can see and feel.
Edema with a lengthy spot |
Now, while edema isn’t a disease, it’s more of a sign that our cactus might not be in the best living conditions. If you see these signs, it’s a good idea to check how often you water and make sure the pot has good drainage. You can keep your cactus from getting edema in the future by making sure it gets enough water and doesn’t sit in soggy soil. Remember, cacti like to dry out a bit between waterings – they’re desert plants, after all!.
Reason 5: Fungal or Bacterial Infections
If you’ve seen strange white spots or fuzzy white growth on your cactus, it might face a fungal or bacterial infection. These infections can pop up for various reasons, but often, they’re linked to conditions that are too damp, poor air circulation, or wounds on the cactus. Bacteria and fungi love moist, stagnant conditions, so if your cactus sits in wet soil for too long or the air around it doesn’t move much, these nasties can take hold. Infections might start as soft, watery spots that later turn brown or black. Sometimes, they might even have a white, cotton-like growth on them.
The key to helping a cactus with this problem is to act fast. These infections can spread and seriously harm or even kill your plant if left unchecked. First, ensure the cactus isn’t sitting in wet soil, and the pot has good drainage. If you see infected parts, consider cutting them off with sterilized tools to stop the spread. There are also antifungal sprays available that can help. Keeping the area around your cactus clean, ensuring good airflow, and watering correctly will also help keep these unwelcome guests away in the future.
WHAT ARE THOSE WHITE SPOTS ON YOUR SUCCULENTS? | SUCCULENTS CARE TIPS
FAQ
What is the white scaly stuff on my cactus?
If your cactus is turning white, it could be due to several reasons: Powdery Mildew or Fungal Infection: A white, powdery substance can indicate a fungal infection. This usually occurs in overly humid conditions. Mealybugs or Scale Insects: These pests can leave a white, cottony residue on your cactus.
How to treat white fungus on cactus?
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1. Identify the Fungus:White fungus on cacti can manifest as powdery mildew, says Succulents Box which appears as a white, powdery coating, or as white sticky spots, according to the Lady Bird Johnson Wildflower Center.
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Lady Bird Johnson Wildflower Centerhttps://www.wildflower.orgHow to Control White Fungus on Prickly Pear Cactus? | NPINJul 4, 2013 — When these white sticky spots first start to appear it is best to spray them off the cactus pads with a power nozzle attached at the end of your hose…
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2. Improve Environmental Conditions:Ensure the cactus is in a well-ventilated area with sufficient sunlight.
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3. Mild Cases: Baking Soda or Copper Fungicide:For mild powdery mildew, mix a tablespoon of baking soda with 1/2 teaspoon of dish soap and a gallon of water, and spray the solution on the affected areas. Alternatively, use a copper-based fungicide, available at Planet Desert.
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Succulents Boxhttps://succulentsbox.comHow to Treat Succulent Fungus NaturallyHow to Treat Succulent Fungus Naturally * However, just like any other houseplants, succulents can have problems as well, especially when there’s a change in t…
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4. Severe Cases: Cutting and Re-rooting:If the fungal infection is severe, cut away the affected areas and dust the cut with sulfur to kill any spores. Then, try to re-root the healthy portions.
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5. Preventative Measures:Ensure proper drainage, avoid overwatering, and avoid splashing water on the stems.
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6. Pest Identification:White spots or cottony patches can also be mealybugs or scale insects, which can be treated with insecticidal soap or diluted dish soap solutions, says Debra Lee Baldwin https://debraleebaldwi….
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YouTube · Debra Lee Baldwinhttps://www.youtube.comHow to Treat Cochineal Scale on Cactus – YouTubeJul 1, 2018 — A bit of cocineal (coach-en-ee-al) scale is no big deal, but it does tend to spread and may eventually kill the plant. Your first line of defense is …
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7. Monitoring:Regularly check your cactus for signs of reinfection and adjust your treatment as needed.
Why does my cactus have dry spots?
This usually occurs when a cactus is abruptly moved from a shaded or low-light area to a location with stronger, more intense sunlight. The harsh rays can scorch the plant, resulting in discolored spots or dry, crispy patches on the surface.
How do you treat dry rot on cactus?
… the bottom of the stems or the crown root, you can first try to save it by applying fungicides, reducing watering, and moving your plant to an airy, dry spot.