Rose Anthracnose or Spot Anthracnose Growing Roses in Iowa Anthracnose or Spot Anthracnose Anthracnose or spot anthracnose is a disease that appears to be more prevalent after a wet springs. Hybrid teas, as well as old fashioned varieties, are susceptible. World-wide, this disease seems to be of little importance as there is virtually no documentation of it in the literature. Symptoms occur as leaf spots, sometimes running together, they usually are 0.5 centimeters in diameter, circular with dark red margins. Newly formed spots are red or purple.
Older spots have white centers with a dark-red margin.
Defoliation may occur if the disease is severe.