Bacterial Bulb Rot

This disease is caused by a bacteria called Erwinia carotovora . The bulbs of infected plants turn soft and pulpy and yellowish in colour . In later stages , a foul smelling liquid starts to ooze from the bulbs . The disease is said to be incurable , but spraying with Agrimycin is reported to have certain beneficial effects .

Another closely related bacterium , Bacterium cypripedii causes brown rot of Paphiopedilums . It spreads rapidly, reaches the crown in no time and kills the plant .

Bacterium oncidii which causes bright yellow spots to appear on leaves of Oncidium, Phytomonas cattleyae which produces brown spot on Cattleya and the bacterium which causes the scorch in Miltonia are other bacterial pathogens which damage the cultivated species. In all bacterial diseases , the pathogen enters the plant through wounds.