Marigolds are bright and attractive followers from the daisy family. They are used as ornamental or decorative plants and are ideal as edging or also for landscape flowers. However these bright lovely flowers have their own problems and diseases.
Marigold enthusiasts should be vigilant about the fungal diseases with the marigolds. These plants are prone to botrytis blight and powdery mildew, both are fungi forms and causes discoloration of the plant that may lead to death in the plant if left untreated.
Botrytis blight is a type of fungal disease that affects all the parts of the plant except the roots. The fungus grows and thrives during the rainy and cool weather conditions. They appear as gray spores and dust-like. Oedema is another disease in the marigold that occurs if the roots absorb too much water. The water pressure in the plants makes them build mesophyll under the leaf of the plant. They turn brown and cause the leaves to turn yellow and fall off. Powdery mildew is another fungal disease that is similar to a white powder on the surface of the flowers and the leaves. However, if kept indoors, they can appear anytime during the year.
Aphids are soft bodied insects that attack marigolds. They appear white, green, red, yellow or brown in color. They cluster on young stems or leaves and suck the juice causing the leaves to dry and eventually fall off. Caterpillars also target marigolds, especially the American marigolds. They finish off the foliage and should be treated immediately. The Japanese beetles may also settle for American marigolds. They create holes by chewing the flowers and foliage. Another bug that should be watched for is the leafhopper. It is a 1/3 inch long wedge-shaped bug that comes with wings. They thrive on leaves and suck into them to make them dry and wither away. Some of them also spread virus diseases like aster yellows.
There are many such problems that should be tackled immediately to make your plant grow healthy with lots of blooms.
The marigolds may slow down due to high summer and may even stop blooming. After the temperature cools down, the marigolds start blooming again. Fluctuations in temperatures make the flowers change the color and temperatures from hot to cold may make the flowers become paler.
Marigolds should not be over fertilized as they may produce copious amounts of foliage and very less blooms. Gardeners should feed only one dose of slow fertilizer every season.