Fasciation (shoot proliferation) can be caused by bacteria, viruses, and phytoplasmas.
Rhodococcus fascians causes leafy galls and shoot proliferation and infects both monocots and dicots of over 60 species of plants. The pathogen, a bacterium, is often mistakenly identified as crown gall (Agrobacterium tumefaciens), but crown gall symptoms are swelling of tissue into tumors or galls on stems or roots. The bacteria may persist in the soil where diseased plants have been grown for one to two years and may move passively in water. The bacteria are primarily limited to surfaces of the plants and there is no evidence of systemic infection. The primary means of spread is by taking cuttings from infected plants and R. fascians can be present on plants for months before symptoms develop. There are no good chemical control products at this time, prevention and sanitation are the primary means of control. Remove and destroy diseased plants and their nearest neighbors. Clean up and discard all plant debris. Keep plants off the greenhouse floor as runoff water can disperse the bacteria. Frequently sterilize cutting tools during propagation. Start with clean planting materials and do not take cuttings from symptomatic plants or those in close proximity to affected plants.
