A COMPENDIUM OF TROPICAL PLANT DISEASES AND DISORDERS
Crown gall is caused by a plasmid carried by the bacterium Agrobacterium tumefaciens . Crown gall is generally more common in woody plants and the disease is more prevalent in field grown nurseries and landscapes than in soilless media free of the bacterium. Olive knot is caused by Pseudomonas savastonoi and was originally found on olives. It has been found on several tropical plants, some of which also can have crown gal. BACTERIAL GALLS - CROWN GALL AND OLIVE KNOT
SYMPTOMS
Crown galls are usually corky appearing tan in color, with a dryish texture.
They form on stems, petioles and leaves of infected plants.
Galls on leaves usually appear at a point where the main vein was damaged Aerial galls are quite common on Ficus benjamina which is not unique for crown gall.
On some crops (like roses) galls can be found on roots.
Symptoms of olive knot are very similar and telling the two apart by sight is not possible.
Galls often form on cutting ends and stem tips where cuttings were removed
FAVORABLE CONDITIONS
Disease outbreaks are favored by environmental stress (i.e., cold, heat, drought)
FICUS CROWN GALL
MANDEVILLA CROWN GALL
OLEANDER OLIVE KNOT
The bacterium infects stems and roots through wounds
The bacterium can be easily spread on tools
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ROSE CROWN GALL
ROSE ROOT AGRO
PHOTINIA CROWN GALL
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