Symptoms and Control Methods of Carnation Leaf Spot Disease

There are many types of pests and diseases that harm carnations, and unsuitable cultivation environments and management mistakes can both aggravate pests and diseases.

Carnation leaf spot disease, also known as carnation white star disease, can harm many flowers of the Caryophyllaceae family.

[Pathogen] Septoria dianthi Desm., belonging to the fungi Deuteromycotina, genus Septoria.

[Symptoms] The disease harms leaves and stems. Nearly round small spots form on leaves and stems, with a diameter of about 5 mm; the spots are light brown with purple edges, and the center may appear white because the epidermis separates. Lower leaves of the plant are more severely affected. If the spots expand, the leaf tips may die. In the late stage of the disease, pinpoint-like black dots can be seen on the spots, which are the pathogen's pycnidia.

[Occurrence Pattern and Epidemic Characteristics] The pathogen overwinters on diseased plant tissues or on diseased residues in the soil. Conidia are spread by rain or sprinkler irrigation water and invade the host through stomata.

[Control Measures] A. Promptly prune diseased leaves or diseased plants to reduce sources of infection. B. When cultivating in a greenhouse, maintain ventilation to keep leaves dry and prevent disease spread. C. In early spring, Bordeaux mixture (1:0.5:100) can be sprayed for protection; when the disease is relatively severe, 70% ferbam 1000-fold solution or mancozeb and other agents can be sprayed for control.