Diseases of mulberry (
Ganoderma root rot
Ganoderma root rot of mulberry is caused by the soilborne fungus Ganoderma lucidum. The fungus is soilborne and infects roots, particularly at wound sites. It causes a slow decline and death of mature trees (photo 1 and 2). The fungus has not been found in upper parts of the tree. The only distinguishing sign of disease is the appearance of fruiting bodies at the base of the tree (photo 3). These growths are most common during the summer rainy season, and start out as white bulbous structures at soil level (photo 4). If they continue to grow, the fruiting bodies become shelf-like structures that are reddish brown and glossy on the top and brown on the bottom. Spores released from the bottom may leave a reddish brown dust on the soil and trunk nearby.
There is no recommended treatment for infected trees; infections may be prevented by preventing wounds to roots and to the trunk at the soil level. Since the fungus survives in the roots of dead trees, it is important not to replant a susceptible plant in the same site. Host plants are probably numerous and include cottonwood, olive, grape, carob, willow, and pyracantha.
February 21, 2013