Root Rot

Overwatering

To address root rot in rex begonia, first, stop watering immediately and allow the soil to dry out. If the plant is severely affected, remove it from its pot, trim away any black, mushy roots, and repot in fresh, well-draining soil. Ensure the pot has adequate drainage holes. Going forward, water only when the top inch of soil feels dry to the touch and consider using a pot with better drainage or a soil mix that promotes aeration.

Leaf Curling and Dropping

Underwatering

Rex begonias require consistent moisture to thrive but are sensitive to both over and underwatering. If you notice leaf curling or dropping, it's a sign of stress, possibly due to insufficient water. To remedy this, establish a regular watering schedule, allowing the top inch of soil to dry out between waterings. Use lukewarm water to avoid shocking the plant's roots. If the soil has been dry for an extended period, soak the pot in a tray of water for an hour to rehydrate evenly.

Spider Mite Infestation

Spider mites are tiny pests that thrive in warm, dry conditions. They feed on the sap of rex begonia leaves, causing them to look speckled, yellow, or bronzed. Severe infestations can lead to leaf drop.

To combat spider mites, increase humidity around your rex begonia, as these pests prefer dry conditions. Regularly misting the plant can help. For minor infestations, wipe the leaves with a damp cloth or rinse the plant under a gentle stream of water to dislodge the mites. For more severe cases, use insecticidal soap or neem oil, applying it according to the product instructions. Ensure to treat the undersides of the leaves where mites commonly reside.

Powdery Mildew

Fungal infection

Powdery mildew on rex begonia is a common fungal issue that manifests as white, powdery spots on leaves. To manage this, ensure good air circulation around your plants and avoid overhead watering to keep the foliage dry. Infected leaves should be removed and disposed of promptly. For severe infections, apply a fungicide specifically labeled for powdery mildew, following the manufacturer's instructions carefully. Prevention is key, so maintain a clean growing environment and quarantine new plants before introducing them to your collection.