Marigold Diseases

Informational table showing disease name, symptoms, pathogen/cause, and management of Marigold diseases.
Marigold Diseases - Articles

Updated: November 2, 2017

Marigold Diseases
DiseaseSymptomsPathogen/CauseManagement
Alternaria Leaf SpotPurplish spots form on leaves and stems.AlternariaAvoid overhead irrigation. Apply fungicide registered for use on this crop.
Bacterial Leaf SpotSmall (2-5 mm) circular dead spots form on leaves and petioles. Spots have purple margins.Pseudomonas tagetisDestroy infected plants. Avoid overhead irrigation.
Botrytis Flower BlightFlower parts brown and die. Gray masses of spores form on the infected tissue when wet.Botrytis cinereaAvoid overhead irrigation. Apply fungicide registered for use on this crop.
Fusarium WiltSeedlings are killed. In older plants, black streaks darken the vascular tissue up one side of the plant. Plants wilt. Roots on the greatly reduced root system are rotted. During wet weather, salmon-colored spore masses form on infected stems.Fusarium oxysporumPlant in potting mix free of pathogens. Destroy infected plants.
Leaf BurnThe tips and margins of leaves yellow and die.Excess boron, manganese, or molybdenumMeasure and apply micronutrient solutions carefully. Manganese should not be above 55 ppm, molybdenum above 24 ppm, or boron above 3 ppm.
Septoria Leaf SpotOval to irregular gray to black spots with tiny dots peppering their surface (fungal fruiting structures) form first on lower leaves and then spread upward.Septoria tageticolaAvoid overhead irrigation. Apply fungicide registered for use on this crop.


Alternaria leaf and stem spot.

Prepared by Gary W. Moorman, Professor of Plant Pathology