SUNFLOWER DISEASE MANAGEMENT

            Pat Donald, Department of Plant Pathology
                 University of Missouri-Columbia
                         (573) 882-2716

     Sunflowers are raised primarily for bird seed in Missouri. Due
to the distance to a seed crushing facility for oil extraction, it
is not economical to produce sunflowers for oil. Sunflower is a
plant native to North America and grows wild in many areas. In the
16th century, sunflowers were taken from America and throughout
trade routes gaining wide acceptance especially in eastern Europe.
Sunflower is widely grown in the world where the climates are not
ideal for soybean production.
     It has not been determined whether American domestication of
the sunflower originated in the southwest, or in the Mississippi or
Missouri River valleys. Cultivated sunflowers were used by early
American settlers as a supplemental food before expansion of the
popular plant into the home garden. 
     Major United States sunflower production is grown under
contract. Sunflowers can be grown as an alternate crop, as a double
crop, or as an emergency crop after the primary crop has been
destroyed.
     Because sunflowers are native to North America and have
evolved with plant pests, there are more sunflower diseases found
in North America than in other parts of the world.
     There are 30 or more known sunflower diseases but nine
diseases are the most commonly seen. Six of the most common
diseases that threaten sunflower yields and are: downy mildew,
rust, Sclerotinia, Verticillium wilt, Phoma, and Alternaria spot.
Septoria leaf spot, powdery mildew, Rhizopus head rot, and charcoal
stem rot are occasionally observed but seldom cause more than very
localized yield reduction.
     Fungicidal protection against foliar diseases in sunflower is
not normally economical. The exception is when new rust races
develop and before resistance genes have been incorporated into
commercial varieties. Seed treatment can be economical in areas
prone to downy mildew. Growing resistant varieties and using pest
management practices are the best ways to maximize yield.
Disease resistance genes are present in many sunflower hybrids for
the following diseases: rust and Verticillium wilt.

ADDITIONAL INFORMATION
     Additional information on sunflower production, diseases and
insects is contained in Extension Bulletin #25 from North Dakota
State University, Fargo, ND 58102. 

ACKNOWLEDGMENTS
     The author thanks Dr. Berlin Nelson, North Dakota State University,
for reviewing the sunflower disease management tables; and Jeanne Mihail
and Rob Myers for their contributions to the original manuscript.