The disease is found in conditions if high humidity, especially in poor ventilated greenhouses or where the ventilation is not controlled properly. Optimum temperature for disease development is between 24-27°C (75.2 - 80.6°F)Bradbury, J.F. 1967. Pseudomonas lachrymans. Description of Pathogenic Fungi and Bacteria, No 124. Commonwealth Mycological Institute, Kew, England. It is caused by Pseudomonas syringae pv. lachrymans [...]