Diseases of Marigold
1. Alternaria blight Alternaria alternata
Symptoms
Circular to irregular tan to brown/purplish spots develop on leaves and stems. These can vary in
size, color, and number, depending upon the pathogen. It also leads to flower blight at later
stages.
Management
Avoid overhead irrigation.
Efforts to maximize plant vigor by fertilizing and watering are helpful.
It is also helpful to pick and remove symptomatic leaves as soon as they develop.
Applications of fungicides like chlorothalonil and thiophanate-methyl.
Spray with Dithane M-45 fungicide @ 0.2% at fortnightly intervals starting from the first
appearance of disease symptoms.
2. Botrytis Blight or Gray mold Botrytis cinerea
Symptoms
Disease symptoms appeared as dead blotches on leaves, flowers, and stems. Rotting of stems
may cause plants to collapse, flower buds may fail to open and diseased flowers that open
become decayed and drop prematurely. A covering of gray fuzzy fungal growth and spores
appears on infected plant tissue
Management
Good sanitation practices including grooming the plants and removing spent or senescing
flowers can minimize the potential for infection.
Avoid overhead irrigation. It is also important to avoid wetting the flowers when watering and
crowding plants.
Adequate spacing between the plants can promote good air circulation.
Control can also be achieved with the use of fungicide sprays applied as soon as symptoms are
visible with iprodione, chlorothalonil, and thiophanate-methyl.
1. Alternaria blight Alternaria alternata
Symptoms
Circular to irregular tan to brown/purplish spots develop on leaves and stems. These can vary in
size, color, and number, depending upon the pathogen. It also leads to flower blight at later
stages.
Management
Avoid overhead irrigation.
Efforts to maximize plant vigor by fertilizing and watering are helpful.
It is also helpful to pick and remove symptomatic leaves as soon as they develop.
Applications of fungicides like chlorothalonil and thiophanate-methyl.
Spray with Dithane M-45 fungicide @ 0.2% at fortnightly intervals starting from the first
appearance of disease symptoms.
2. Botrytis Blight or Gray mold Botrytis cinerea
Symptoms
Disease symptoms appeared as dead blotches on leaves, flowers, and stems. Rotting of stems
may cause plants to collapse, flower buds may fail to open and diseased flowers that open
become decayed and drop prematurely. A covering of gray fuzzy fungal growth and spores
appears on infected plant tissue
Management
Good sanitation practices including grooming the plants and removing spent or senescing
flowers can minimize the potential for infection.
Avoid overhead irrigation. It is also important to avoid wetting the flowers when watering and
crowding plants.
Adequate spacing between the plants can promote good air circulation.
Control can also be achieved with the use of fungicide sprays applied as soon as symptoms are
visible with iprodione, chlorothalonil, and thiophanate-methyl.
