Histopathology of grapevine inoculated with Lasiodiplodia theobromae

Abstract

Histopathological changes of 2-years old grapevine cv. Abbassi inoculated with Lasiodiplodia theobromae (syn. Botryodiplodia theobromae) were studied. Samples were taken at 7 and 25 days after artificial inoculation. At 7 days, cross and longitudinal sections revealed the presence of disorganized cells, degenerated areas and vascular bundles. The intra and intercellular invasion of the inoculated tissues by the fungus were evident with dark brown color. At 25 days, the fungus caused necrosis in xylem parenchyma and xylem vessels, the hyphae colonized the tissues. Dark deposits appeared in vessels and other tissues as well as abundant production of tyloses. L. theobromae has also been found to produce pycnidia on the shoots and petioles of grapevine which yielded 2-celled dark pycindiospores. After more than 4-weeks, the inoculated grapevine seedlings look flaccid, brown in color and wilting symptoms began to appear and finally the seedlings were dead.