Lesions on the corms are light-colored, watery spots at first and become darkened with a raised margin, the center of which shows a hard, gummy exudate which is shiny and reddish. The most effective method for control of this disease is selection of a site with well-drained soil. It is also very important to discard any corms that show disease symptoms. Bacterial blight, Xanthomonas . This disease is usually only a problem during years with excessive rainfall.
Infestation can result in significant damage to the foliage, particularly in closely planted stock.
Spots first appear as small, elongated, water-soaked marks in the form of irregular, angular lesions between the veins. As they age, they become brown to black and develop a yellow margin. The most effective method for control of this disease is selection of a site with well-drained soil. It is also very important to discard any corms that show disease symptoms. Symptoms appear as a light and dark green mottling or a mosaic pattern on the leaves.