Exacum Disease Management: Stem Rot, Botrytis, and Pythium Control

Managing Diseases in Exacum (Persian Violet) Production

Exacum faces three primary disease threats: basal stem rot/branch blight, Botrytis blight, and Pythium root rot. High temperature stress and high humidity create favorable conditions for these pathogens in greenhouse production.

Basal Stem Rot and Branch Blight

Nectria haematocca rapidly kills wounded stems at high temperatures.

Management: Maintain moderate temperatures. Avoid wounding plants during handling.

Botrytis Blight

Botrytis cinerea rots established plant stems at soil line, often at flowering, killing entire plants.

Management: Heat and ventilate for low humidity. Remove dead/dying tissue from greenhouse. Apply protective fungicides.

Pythium Root Rot

Pythium spp. cause wilting, collapse, and death with water-soaked, limp, brown roots.

Management: Use pasteurized potting soil. Discard infected plants.

Integrated Exacum Health Program

Successful Exacum production requires: moderate temperature management (avoid heat stress); careful handling to prevent wounding; low humidity through heating/ventilation; strict sanitation (remove dead tissue); pasteurized media; and preventive fungicide applications. The combination of high temperature stress (predisposing to Nectria) and high humidity (favoring Botrytis and Pythium) makes environmental control the cornerstone of disease management for this crop.