What's eating my begonia 'glowing embers'?

Begonia 'Glowing Embers', a Rieger/hiemalis begonia sold as a flowering houseplant, is highly prone to powdery mildew and botrytis in cool, humid rooms. Mealybugs and vine weevil (whose larvae attack roots) are also a concern. Keep air circulating, avoid wetting flowers or foliage, and inspect roots at repotting.

White floury patches on leaves and stems; tissue distorts and browns Improve ventilation; avoid overhead watering; remove affected material; spray with potassium bicarbonate or sulfur fungicide

Grey fluffy mould on spent flowers and soft stem tissue in cool damp conditions Remove dead flowers promptly; increase airflow; reduce humidity at night; apply copper-based fungicide if severe

Cottony colonies at stem bases and growing tips; leaves yellow and drop Remove with alcohol swab; spray neem oil; treat soil with Bti drench if soil pests co-occur

Notched leaf margins from adult beetles; plant suddenly collapses as larvae eat roots Apply Steinernema kraussei nematodes to moist compost in autumn; use vine-weevil killer drench as a preventive