Diseases of Grapevine in Missouri
by Laszlo Kovacs

Black rot is the most important limiting factor of grape production in Missouri. It develops in every growing season, and, if left uncontrolled, it will destroy fruit on most cultivars. The development of the pathogen is favored by the weather conditions during most of the summer, and therefore the application of a preventive spray schedule during the susceptible growth stages is essential. In fact, the chemical control of black rot should form the backbone of the spray schedule from mid-bloom until veraison. Because the disease buildup can be explosive, the appearance of symptoms in the vineyard calls for an immediate application of Nova, the most effective curative fungicide. The only cultivar that possesses good genetic resistance to this disease is Norton/Cynthiana.