What are the common fungal diseases of flowers? How to prevent it?

Fungal diseases are the most common diseases in flowers, accounting for about 90% of flower diseases. Common powdery mildew, anthracnose, gray mold, leaf spot and so on.

(1) powdery mildew.

Powdery mildew is the most common disease of flowers, which mostly occurs in rose, chrysanthemum, dahlia, chrysanthemum and gerbera. It mainly harms young leaves, buds, branches, buds and pedicels. At the initial stage of the disease, chlorosis spots appeared on the affected parts, then gradually turned into white powder, and the diseased spots turned gray in the later stage. Diseases often cause short flowers, bent tender tips, few flowers that are small or can't open, and uneven leaves. In severe cases, the leaves are curly and dry, and even the whole plant dies (see the picture below).

Color picture 49 Lagerstroemia indica powdery mildew

(2) anthrax.

More common in orchids, clivia, cyclamen, cockscomb and so on. It mainly harms leaves, but also infects stems, tender shoots, flower buds, fruits and other parts. At the initial stage of the disease, it starts from the tip and edge of the leaves, and there are nearly round lesions on the leaves, with purple-brown edges and light brown or grayish white centers. In the later stage, black spots are formed on the diseased spots, which are arranged in a wheel shape, and in severe cases, the leaves die (see the figure below).

Orchid anthracnose color map 50

(3) gray mold.

Gray mold mostly occurs in cyclamen, dahlia, chrysanthemum, gerbera, rose, chrysanthemum, gladiolus, rhododendron, poinsettia, lily and so on. It mainly harms leaves, stems, flowers and fruits. Generally, water-stained spots appear at the initial stage of the disease, and then gradually expand into brown or purple-brown spots. When the weather is wet, fine gray hairs grow on the diseased spots, and in severe cases, the whole plant dies (see the picture below).

Color Figure 5 1 Rose Red Gray Mold

(4) leaf spot disease.

Leaf spot disease is a spot symptom caused by local cell necrosis on leaves of flowers infected by different pathogens. Common diseases are angular leaf spot, stripe disease, circular leaf spot, gray spot disease, black spot disease and brown spot disease, among which fungal leaf spot disease is more common and has serious harm, which is mainly divided into black spot disease and brown spot disease. Black spot disease mainly harms canna and rose. After the onset, nearly round or irregular black, purplish brown or dark brown spots appear on the leaves, and in severe cases, the leaves turn yellow and fall off. Brown spot disease mainly harms poinsettia, rhododendron, rose, chrysanthemum, gerbera, cockscomb and so on. After the onset, round or nearly round black-brown and brown spots appear on the leaves, which can cause a lot of scorching of the leaves in severe cases (see the figure below).

Color map 52 rose black spot disease

Color picture 53 Rhododendron brown spot disease

Control methods: ① During the growth of flowers, spray 400-600 times of 65% zineb wettable powder/kloc-0 every 7-0 days for 3-5 times continuously to achieve the control effect. (2) Cut off diseased branches and leaves in time and destroy them centrally. Thoroughly remove garbage in winter and spring. ③ Pay attention to ventilation and light transmission, reasonable water and fertilizer, and improve disease resistance. ④ Spraying 50% carbendazim 500-800 times or 75% chlorothalonil 600-800 times at the initial stage of the disease. To control botrytis cinerea, 70% pentachloronitrobenzene and 80% zineb can be mixed evenly to disinfect the soil, and the dosage is 8 ~ 10g per square meter.