Root Rot

Overwatering

To address root rot in fairy castle cactus, first, stop watering immediately and allow the soil to dry out completely. If the plant is severely affected, remove it from its pot, trim away any black, mushy roots, and repot in fresh, well-draining cactus mix. Ensure the pot has adequate drainage holes. In the future, water only when the top inch of soil feels dry to the touch, and reduce watering frequency in cooler months.

Shriveling and Discoloration

Underwatering

To address shriveling and discoloration caused by underwatering in fairy castle cactus, gradually increase watering frequency without overdoing it. Start by soaking the soil thoroughly until water runs out of the drainage holes, then allow it to dry out completely before the next watering. This process might need to be adjusted based on the season, with less water required during winter. Monitoring the soil moisture can be a good practice to ensure the cactus receives the right amount of water.

Mealybug Infestation

Mealybugs are small, white, soft-bodied insects that feed on the sap of the fairy castle cactus, often hiding in crevices.

To combat mealybugs, first isolate the affected plant to prevent spread. Use a cotton swab dipped in alcohol to dab directly onto the pests, effectively killing them without harming the plant. For severe infestations, applying a diluted solution of neem oil or insecticidal soap directly to the plant every 7-10 days for a few cycles can help eradicate these pests. Ensure to cover all surfaces of the plant for the treatment to be effective. Regularly inspect your plant for early signs of return.

Sunburn

Excessive direct sunlight

Fairy Castle Cactus enjoys bright but indirect sunlight. If your plant shows signs of sunburn, such as yellowing or brown spots on the most exposed areas, it's crucial to relocate it to a spot with filtered light. Gradually acclimate it to any new lighting conditions to prevent shock. For severe sunburn, prune the damaged areas to prevent potential infection, ensuring to use sterilized tools. Regularly rotating the plant can also ensure even light distribution and prevent future sunburn.