Sclerotinia wilt and head rot are generally the most important diseases affecting sunflowers.
National Sunflower Association of Canada Agronomist Troy Turner says sclerotinia is found in most soils, however it doesn't usually develop in sunflower fields due to the wide row spacing and drier soil.
"Where we usually see it develop, is in the neighbouring fields of wheat or oats or heavy canopies of canola and the spores get up and moving into the fields and infection can take place on your heads," explained Turner.
Turner says crop rotation is very important in helping to fight diseases like sclerotinia. He notes its important to try to keep four year in between crops that are susceptible to the disease, including sunflowers.
Source : Portageonline