If you are in commercial marigold farming, then you must control the diseases and pests. This article includes a list of important marigold pests and diseases. Additionally, how you can control the pests, insects, and disease attacks with a complete plant protection guide.
Generally, Marigold is relatively free from diseases and insect pests. However, occasionally, you can observe the following diseases and insect- pests on the farm.
Potential & Harmful Diseases in Marigold Plant
#1. Damping-off (Pythium sp.)
The disease is most prevalent at the seedling stage. Necrotic spots and rings develop on the young seedlings causing a collapse of the seedlings. You can face a considerable loss if you do not properly look after the seedlings.
To control, you can apply soil sterilization by Formalin @ 2% before sowing and spraying of Dithane Z-78 @ 2g/ liter of water.
#2. Flower bud rot (Alternaria Dianthi):
The fungus infects the young flower buds. The infected buds shrivel and become dark brown in color. The pathogen also infects leaves causing blight. The infection is visible in the form of brown necrotic spots on the margins and tips of older leaves.
Spraying of Mancozeb (2g/ liter of water) effectively controls the flower bud and leaf infections.)
#3. Leaf spot &blight (Alternaria, Cercospora, and Septoria sp.)
Brown necrotic spots develop on leaves, which get enlarged at the later stage of infection. The entire foliage gets damaged and results in poor vegetative growth.
Spraying of Dithane M-45 @ 0.2% at regular intervals is helpful.
#4. Wilt and Stem Rot (Phytophthora Cryptogea)
The fungus affects the collar portions of the plants. In the nursery, the infection results in damping-off and is aggravated by soil moisture. In the field, the infected plants show wilting. French marigold and dwarf varieties are less susceptible whereas the African types are highly susceptible to the disease.
Generally, you can control the disease by soil treatment with Captan and Mancozeb
#5. Collar Rot (Phytophthora sp.; Pythium sp.)
The symptoms are in the form of black lesions developed on the main stem. Rotting at the collar regions causes the death of the plant.
Soil sterilization and controlled watering help in reducing disease incidence.
6. Powdery Mildew (Oidium sp.; Leveillula Taurica)
The symptoms are in the form of whitish powdery growth on the aerial parts of the plant.
Spraying Sulfex (3g/ liter of water) can effectively control the disease.
Marigold Pests & Insects Attacks & Control
#7. Red spider mite
These mites sometimes appear on the plants near flowering time. Plants give a dusty appearance.
Generally, you can control this by spraying Metasystox 25 SE/Rogor@ 1 ml /lit. of water.
#8. Hairy caterpillar
It is a polyphagous insect and caterpillar eats away the foliage. You can control these caterpillars by spraying Thiodan 35 EC @ 1 ml/lt. of water.
In most cases, proper farm management helps to reduce the marigold pests and disease attacks. However, after observing the attack you must take proper plant protection methods to minimize the loss.