First Report of Stalk Rot Disease of Sugarcane Caused by Phaeocytostroma sacchari in Mexico

In April 2009 and 2010, severe symptoms of stalk rot of sugarcane (Saccharum officinarum L.) plants cvs. MEX-79-431, MEX-69-749, and RB-73-9735 were observed in commercials fields located in southeast Michoacan state, Mexico. The diseased plants exhibited complete discoloration of foliage, ascendant necrosis and rot in the internal stalk tissue, and disintegration of vascular tissue. Symptoms were most evident in the nodes with intense purple coloration. Dead plants were observed. Two diseased plants of each cultivar were collected. Pieces of symptomatic stem tissue were surface sterilized with 2% sodium hypochlorite solution for 1 min, washed with sterile distilled water, dried on sterilized paper, and plated onto potato dextrose agar (PDA). Petri dishes were incubated at 22°C under continuous white light for 72 h. A fungus was consistently isolated. On PDA, colonies had sparse aerial mycelium in the center and dense in the margins with black masses of conidia. The fungus isolated was grown on dishes con...