Root Rot

Overwatering

To address root rot, first, remove the plant from its pot and inspect the roots. Trim away any black, mushy roots with sterilized scissors. Allow the healthy roots to air dry before repotting in fresh, well-draining soil. Use a pot with adequate drainage holes. Going forward, water your ZZ plant only when the top 2 inches of soil are dry, and ensure it's in a location with good air circulation to prevent future occurrences.

Yellowing Leaves

Underwatering

To address yellowing leaves caused by underwatering, ensure your ZZ plant is watered regularly, allowing the soil to dry out slightly between waterings. Use a well-draining soil mix to prevent waterlogging. If the plant is severely dehydrated, immerse the pot in water for a few minutes to rehydrate the soil thoroughly. Adjust your watering schedule according to the season, watering less frequently in winter. Monitor the plant's response and adjust care as necessary to maintain healthy moisture levels.

Mealybugs Infestation

Mealybugs are small, soft-bodied insects covered with a white, waxy substance. They typically infest the crevices and undersides of the zz plant's leaves, sucking sap and weakening the plant.

To combat mealybugs, start by isolating the affected plant to prevent the pests from spreading. Use a cotton swab dipped in rubbing alcohol to dab directly onto the mealybugs, effectively killing them on contact. For more severe infestations, rinse the plant gently with water to remove any visible pests, then apply neem oil or insecticidal soap to the leaves and stems, following the product's instructions. Repeat the treatment every 7-10 days until the infestation is cleared. Regularly inspect your plant for early signs of pests to prevent future outbreaks.

Leaf Spot Disease

Fungal or bacterial pathogens

To manage leaf spot disease, start by removing and destroying any affected leaves to prevent the spread. Improve air circulation around your plant by not overcrowding it with other plants and ensuring it's in a well-ventilated area. Avoid wetting the foliage when watering, as moisture on the leaves can promote the disease. If the infection is severe, applying a fungicide or bactericide, as appropriate, according to the product's instructions, may be necessary. Always sterilize your pruning tools after use to prevent spreading the pathogens.