Chrysanthemum black spot, also known as brown spot, spot blight. The disease occurs in the area of ​​chrysanthemum cultivation. In addition to damaging chrysanthemums, it can also invade various asteraceae plants such as chrysanthemum, chamomile, and pyrethrum. After the plants were damaged, the leaves of the light plants were charred and fell off, and the severe plants died. Seriously affect the growth and appreciation of plants.
Symptoms: The disease mainly damages the leaves of the plants. At the early stage of disease, brown spots were found on the susceptible leaves, and the lesions gradually expanded into round, oval or irregular shapes and black to dark brown. There is a clear boundary between the disease and health departments. In the later stage of the disease, there are less obvious black spots on the lesions, which are pathogenic spores. In severe cases, lesions connect to each other to form large plaques. Finally, the leaves turned black and died, hanging on the stems. The leaves of susceptible plants started from the lower part and withered upwards.
Pathogen: The pathogen is Septoria chrysanthemella Sacc. It belongs to the subphylum Aspergillus spp., Caudatum, Sphaeropsis spp.
Incidence regularity: Pathogenic bacteria use mycelium and conidia to overwinter on diseased plant residues. In the following year, when the temperature is suitable, the pathogenic conidia are mature and produce conidia, and conidia spread through wind and rain. The optimum temperature for the development of pathogens is 22-27°C, and the disease begins about 15-30 days after infestation. The disease can occur throughout the entire growth period of the plant. High temperature and rainy season or planting too dense, the disease develops rapidly. Different varieties of resistance to black spot disease also have some differences. The susceptible species include purple butterfly, new white, fire dance, purple dew cream, crab claw yellow, white pear, Shih drunk dance, and Tian Tianle. The varieties with strong disease resistance include Lake Moon, Spring Dance, Autumn, Jade, Purple Geese, and Purple Gui.
Prevention:
1 Remove pathogens and diseased leaves in time to eliminate the source of infection. Plants that are eliminated after planting should be removed and destroyed in time to reduce the source of infection in the coming year.
2 to strengthen the cultivation and management: select well-drained, airy and translucent areas of planting chrysanthemum. Avoid continuous work. Potted soil should be changed every year. Rational fertilization, pay attention to the ratio of nitrogen, phosphorus, and potassium to promote robust growth of plants and enhance resistance to disease. Do not overtighten the plants so that the plants have adequate ventilation and light transmission.
3 Elimination of disease as soon as possible and species with low ornamental value are eliminated.
4 Chemical control: Before the onset of disease, spray 1:1:100 Bordeaux mixture to prevent infection. In the onset stage, spray 75% chlorothalonil wettable powder 500-800 times, or 80% Captanol wettable powder 500-600 times, or 50% thiophanate-methyl wettable powder 800-1000 times. Spray once every 7-10 days, spray 2-3 times. The use of agents alternately works well.
Symptoms: The disease mainly damages the leaves of the plants. At the early stage of disease, brown spots were found on the susceptible leaves, and the lesions gradually expanded into round, oval or irregular shapes and black to dark brown. There is a clear boundary between the disease and health departments. In the later stage of the disease, there are less obvious black spots on the lesions, which are pathogenic spores. In severe cases, lesions connect to each other to form large plaques. Finally, the leaves turned black and died, hanging on the stems. The leaves of susceptible plants started from the lower part and withered upwards.
Pathogen: The pathogen is Septoria chrysanthemella Sacc. It belongs to the subphylum Aspergillus spp., Caudatum, Sphaeropsis spp.
Incidence regularity: Pathogenic bacteria use mycelium and conidia to overwinter on diseased plant residues. In the following year, when the temperature is suitable, the pathogenic conidia are mature and produce conidia, and conidia spread through wind and rain. The optimum temperature for the development of pathogens is 22-27°C, and the disease begins about 15-30 days after infestation. The disease can occur throughout the entire growth period of the plant. High temperature and rainy season or planting too dense, the disease develops rapidly. Different varieties of resistance to black spot disease also have some differences. The susceptible species include purple butterfly, new white, fire dance, purple dew cream, crab claw yellow, white pear, Shih drunk dance, and Tian Tianle. The varieties with strong disease resistance include Lake Moon, Spring Dance, Autumn, Jade, Purple Geese, and Purple Gui.
Prevention:
1 Remove pathogens and diseased leaves in time to eliminate the source of infection. Plants that are eliminated after planting should be removed and destroyed in time to reduce the source of infection in the coming year.
2 to strengthen the cultivation and management: select well-drained, airy and translucent areas of planting chrysanthemum. Avoid continuous work. Potted soil should be changed every year. Rational fertilization, pay attention to the ratio of nitrogen, phosphorus, and potassium to promote robust growth of plants and enhance resistance to disease. Do not overtighten the plants so that the plants have adequate ventilation and light transmission.
3 Elimination of disease as soon as possible and species with low ornamental value are eliminated.
4 Chemical control: Before the onset of disease, spray 1:1:100 Bordeaux mixture to prevent infection. In the onset stage, spray 75% chlorothalonil wettable powder 500-800 times, or 80% Captanol wettable powder 500-600 times, or 50% thiophanate-methyl wettable powder 800-1000 times. Spray once every 7-10 days, spray 2-3 times. The use of agents alternately works well.
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