What are the two main diseases of carnations?

Carnations are most susceptible to leaf spot and stem wilt, and calyx rot.

The fungal spores of leaf spot and stem wilt persist in carnation plants and in decayed, rotting plants, and spread through the air. When water remains on the plant surface for 8-10 consecutive hours, the pathogen can penetrate through the moisture. The symptoms of leaf spot and stem wilt are: grayish-brown leaves or spots with purple edges appearing on the petals. The spots are formed by clusters of black spores, and the stems begin to yellow and wither from the internodes, then develop into a wilt that encircles the stem completely.

The pathogen of calyx rot persists in the old leaves, lower stems and branches, or decayed and rotting plants of carnations. High-humidity conditions favor the occurrence of the pathogen. Its symptoms are: rot first begins at the tip of the calyx and then spreads toward the base of the calyx. For the control of these two diseases, in addition to necessarily pulling up the weeds around the carnation garden, if carnations are cultivated in a greenhouse, circulating air must frequently be supplied to the greenhouse to keep humidity low. If irrigation is needed, it is best done in the early morning. When irrigating, run two plastic pipes on the ground on both sides of the carnation seedbed ridges, with one flat fan-shaped nozzle installed every 50 cm, at an angle of less than 45 degrees to the ground. This can prevent the irrigation water from wetting the flower foliage. During periods of high humidity, spray or dust with zineb, captan, mancozeb, or folpet.