While they are technically a cactus, Christmas cacti dont naturally live in the desert like other cacti. They originate from coastal tropical rainforests in Brazil. If youre struggling to keep your Christmas cactus happy, here are some of the most common problems that Christmas cactuses have and what to do about them.
The Christmas cactus (Schlumbergera bridgesii) is a popular holiday houseplant prized for its colorful and vibrant flowers that bloom towards the end of December. However, this eye-catching cactus can sometimes develop mysterious white spots on its flattened green stems, marring its beauty. If you’ve noticed these unsightly blemishes on your plant, don’t panic. In most cases, the spots are merely cosmetic damage and not a sign of any serious underlying disease. With some detective work and proper care, your Christmas cactus can often outgrow the problem over time.
In this article, we’ll explore the various causes of white spots on Christmas cactus and effective solutions to fix them.
What Causes White Spots on Christmas Cactus?
White spots or markings on Christmas cactus are usually triggered by one of the following factors
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Sunburn – Too much direct sunlight can scorch or bleach the tender green epidermis of the stems, leaving behind sunken white lesions. This often occurs if the plant is moved from indoors to intense outdoor sunlight without slowly acclimating it first.
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Mineral deposits – White crusty deposits on the surface are generally a buildup of mineral salts like fluoride, chloride and boron. Tap water and softened water contain salts that can leave these marks when allowed to dry on the stems and leaves
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Pests – Sap-sucking insects like mealybugs and scale can feed on plant fluids, causing white spots. Their waxy secretions can also coat stems white.
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Diseases – Fungal infections like leaf spot can create small, round, sunken white spots outlined in black, yellow or reddish halos on stems.
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Root rot – Wet soggy soil and roots can lead to stem and leaf spotting. As the roots rot, the plant is unable to absorb moisture, causing wilt and white patches.
Carefully inspect your plant to accurately identify the cause before treating the spots. Gently rubbing them with your fingers can help determine if it’s pest, fungal or mineral buildup.
How to Treat White Spots on Christmas Cactus
Fix Sunburn Damage
- Gradually acclimatize the plant to increased sunlight over several weeks if moving it outdoors.
- Keep it shaded from intense afternoon sun.
- Indoors, an east or west window is ideal to prevent sunscald.
- Damaged areas will slowly fade or peel away as the cactus produces new growth.
Remove Mineral Deposits
- Water with room temperature distilled or rainwater to avoid adding salts.
- Gently wipe stems with a soft cloth dipped in distilled white vinegar to dissolve crusty deposits.
- Avoid wetting the leaves.
- Improvement will be gradual as affected segments elongate and minerals slowly diminish over time.
- Trim off severely marked stems.
Control Pest Infestations
- Apply insecticidal soap or horticultural oil spray every 7-10 days to kill mealybugs, scales and other sap feeders.
- Systemic insecticides added to the soil may help heavy infestations.
- Isolate treated plants from uninfected ones.
- Remove heavily infested stems to aid control.
Treat Fungal Diseases
- Improve airflow and reduce humidity around the plant.
- Apply copper-based fungicide sprays at first sign of fungal leaf spot.
- Remove and destroy affected leaves and stems.
Fix Root Rot
- Allow potting mix to dry out completely between waterings.
- Replant bare-rooted plant in fresh, sterile mix after trimming all mushy roots.
- Water cautiously, keeping it barely moist, not soggy wet.
- Discard diseased clippings. Sterilize clippers after use.
With some detective work to accurately diagnose the cause, and attentive care to fix underlying issues, your Christmas cactus can regain its flawless beauty. Any white markings should gradually fade away as the plant puts out new healthy growth. With proper growing conditions, you can prevent future blemishes from marring its graceful pendant stems.
How to Prevent White Spots on Christmas Cactus
Here are some tips to keep your Christmas cactus healthy and free of spots:
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Water only when the top inch of soil is partly dry. Allow to drain thoroughly after watering.
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Use well-draining cactus/succulent soil and a container with drainage holes.
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Keep humidity around 50-60% and temperatures between 65-75°F.
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Avoid wetting the leaves when watering.
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Provide bright, indirect sunlight indoors near an east or west window.
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Fertilize monthly in spring and summer with a balanced houseplant food at half-strength.
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Prune right after flowering to stimulate branching and prevent legginess.
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Repot every 2-3 years in spring, avoiding overpotting.
With proper care, your Christmas cactus can thrive and dazzle year after year when it bursts into magnificent bloom just in time for the holidays. Don’t let a few minor cosmetic flaws deter you from growing these botanical beauties.
CHRISTMAS CACTUS LEAVES TURNING RED OR PINK
If the leaves of your Christmas cactus are turning red or pink, it may be getting too much sun, or it may not be getting watered enough.
Solution: If your Christmas cactus is right next to a window that gets direct sun during the day, move it back. They can take a bit of sun, but they prefer indirect light. Check the soil as well, and if its dry to one inch deep, water it more frequently. When the soil feels dry to the touch, water your Christmas cactus.
BOTRYTIS BLIGHT, OR GRAY MOLD
Looks like: a silvery gray fungus or spots of mold all over the leaves
Caused by: Botrytis blight is a fungal infection. It thrives on decaying foliage and spreads as spores. Very high humidity and getting the leaves wet makes a plant more susceptible.
Solution: plants with Botrytis blight should be discarded and destroyed immediately. Make sure to sanitize the pot with bleach if you intend to reuse it. You can help prevent Botrytis blight by improving ventilation and air circulation.
Looks like: yellow spots on wilted leaves and stems.
Caused by: infected thrips.
Solution: isolate your plant and use an appropriate insecticide to deal with thrips. Purchase new soil, and repot your plant in a clean pot. Discard the soil in your garbage bin, tied shut in a black bag. If you want to use the pot again, make sure you sanitize it with bleach.
Here are some of the other non-disease related problems that holiday cactuses may have. These problems are usually easily solved by some adjustments to the environment or care for your Christmas cactuses.
Troubleshooting and Solving Common Christmas Cactus Problems
FAQ
How do you get rid of white fungus on Christmas cactus?
Remove all parts of the plant – roots and stems – that show signs of infection, sterilizing the pruners between each cut. Repot the cactus into fresh potting soil and apply a fungicide drench labeled for treatment of fusarium.
How do you get rid of white spots on cactus?
You should be able to remove them pretty easily with an old toothbrush dipped in diluted isopropyl alcohol. After you get all of the visible critters you’ll want to spray the whole plant with horticultural oil over a few weeks to prevent them from re-establishing. They can be very persistent if you skip this step.
What does an overwatered Christmas cactus look like?
The signs you’re getting it wrong? Overwatered Christmas cacti go limp and the leaves might yellow; underwatered Christmas cacti might shrivel and go brown. As a rule, Christmas cacti only need watering every two to three weeks.
What are the symptoms of the streaking virus in Christmas cactus?
A Christmas cactus infected with a streaking virus may exhibit the following symptoms: Streaking, Yellowing, Ringspots, Mosaic patterns, Deformed growth, Stunting, Necrotic lesions, and Veination. Symptoms may be less noticeable during warmer temperatures.
Why are there white spots on Cactus?
White spots on cactus become an alarming sign when they appear on attractive cacti and ruin the aesthetics of the plant. Cacti require less care, water, and precision than most non-succulent plants making them suitable for busy plant-lovers.
What causes yellow spots on a Christmas cactus?
Yellow spots on a Christmas cactus can derive from several conditions, including root rot, sunburn, or stem rot. However, the last one, Basal stem rot, can potentially be deadly for your plant if not treated immediately, so you should check for signs of this disease before treating your plant for secondary issues.
What causes brown spots on Christmas cactus leaves?
Brown spots on the leaves of your Christmas cactus are common. They can be the consequence of sunburn or sunscald, especially if they appear where the leaves are at their thinnest, usually along the edges. However, in most cases, these spots are relatable to Botrytis blight, a fungal disease that affects millions of plants worldwide each year.
What causes white spots on a prickly pear cactus?
Based on observation, the main reasons for white spots on a prickly pear cactus include fungal infections, sunburn, pests, or physical damage. Fungal infections can cause white patches or powdery substances on the Cactus’s surface. Sunburn can lead to white or pale spots on the Cactus where the sun’s rays have damaged the tissue.
Why are there spots on my Christmas cactus?
Sometimes, the lesions are the result of an infestation of bugs, such as mealybugs. The appearance of spots on your Christmas Cactus can derive from environmental factors such as overwatering in the case of Stem Rot. However, other aspects to watch out for include poor air circulation, low temperatures, improper light conditions, and high-humidity.
How do I know if my Christmas cactus has pests?
I’ll guide you through identifying common pests and troubleshooting problems caused by environmental factors. Pests such as aphids, mealybugs, thrips, and fungus gnats can wreak havoc on your Christmas cactus. Early detection is key to preventing an infestation. Mealybugs: Look for white, cotton-like masses on your plant.