Diseases associated with holiday cactus are: Fusarium oxysporum, Phytophthora parasitica and Pythium aphanidermatum, Bipolaris cactivora, and Erwinia carotovora.

Fusarium oxysporum is a root or stem rot fungus. Infected parts produce reddish-orange sunken spots. Orange spores develop in the lesions and are spread easily by water or air. When the basal segment becomes infected, the stem falls over.

Phytophthora parasitica and Pythium aphanidermatum are fungi that produce root or stem rots. These diseases are characterized by dead stem lesions with faded reddish borders, grey-green discoloration of the stems, and segment abscission. Bipolaris cactivora is a fungus that causes stem rot. Symptoms include blackened, sunken lesions up to ½" in diameter. Black spores develop in the lesions.

Erwinia carotovora is a bacterium that causes soft rot in numerous cacti, including holiday cactus. The initial symptom is usually a blackened, wet, slimy lesion that develops on the basal segment and progresses upward in the shoot. Plants wilt, collapse, and usually die. Bacteria are spread by splashing water. Since this disease is caused by a bacterium, fungicides will not control the disease.

The key to disease prevention is not to over water your plant. Provide good drainage and keep the plant in bright indirect light. There are fungicides available for use on some of the diseases, but prevention is the best solution.

Reference: UMass extension website. Prepared by Thomas H. Boyle, Department of Plant and Soil Sciences. September 1993.