Symptoms
Mainly harmful to the leaves, also known as leaf blight. From the lower part of the plant, the lesion develops upwards, and the lesion is round yellowish, water-soaked, with obvious edges, and later developed into an irregular shape. The color of the plaque is changed from light yellow to grayish white, and small black spots are formed on it, which is a conidia of the pathogen. When the petiole and stem are damaged, the lesion is oval, slightly darker and slightly concave. There is often a circle of yellow halos around the lesions, and conidia occur mostly around the markings, crowded together. When the disease is serious, the leaves are dry.
2. Routes of transmission and disease conditions
The hyphae are lurking in the seed coat, attached to the seed, the diseased body or overwinter on the seeding root. The hyphae lurking in the seed coat survived for more than one year, and the pathogen attached to the seed surface survived for more than 2 years, and the conidia on the lesion survived for 8 to 11 months. The pathogens are suitable for the environment, that is, the conidia and conidia are formed, which are spread by wind and rain, humans and animals, tools, etc., and the conidia of the water droplets sprout, causing the germ tube to invade from the pores or penetrate the cortex. The disease is prevalent in colder climates with temperatures of 20 to 25 °C, heavy rain or high humidity. The temperature difference between day and night is large, and condensation occurs at night, which lasts for a long time and has a serious incidence.
3. Prevention methods
a. Collect seeds from disease-free and disease-free plants. Use the seeds within two years, soak them in warm water at 48-49 °C for 30 min, stir while stirring, then transfer to cool water to cool, dry and sown.
b. Implement 2 to 3 years of rotation, apply enough base fertilizer, and timely topdress. Avoid flooding with large water, drain after rain, and protect the ground from ventilation and drainage. c. Spray 75% chlorothalonil WP 600 times solution or 1:0.5:200 Bordeaux solution or 50% sulfur suspension agent 200-300 times solution or lime sulfate copper sulphate powder (30 parts of lime and 10 parts of copper sulphate) , sulfur powder 10 parts), etc., spray every 7 to 10d, a total of 2 to 3 times.
Mainly harmful to the leaves, also known as leaf blight. From the lower part of the plant, the lesion develops upwards, and the lesion is round yellowish, water-soaked, with obvious edges, and later developed into an irregular shape. The color of the plaque is changed from light yellow to grayish white, and small black spots are formed on it, which is a conidia of the pathogen. When the petiole and stem are damaged, the lesion is oval, slightly darker and slightly concave. There is often a circle of yellow halos around the lesions, and conidia occur mostly around the markings, crowded together. When the disease is serious, the leaves are dry.
2. Routes of transmission and disease conditions
The hyphae are lurking in the seed coat, attached to the seed, the diseased body or overwinter on the seeding root. The hyphae lurking in the seed coat survived for more than one year, and the pathogen attached to the seed surface survived for more than 2 years, and the conidia on the lesion survived for 8 to 11 months. The pathogens are suitable for the environment, that is, the conidia and conidia are formed, which are spread by wind and rain, humans and animals, tools, etc., and the conidia of the water droplets sprout, causing the germ tube to invade from the pores or penetrate the cortex. The disease is prevalent in colder climates with temperatures of 20 to 25 °C, heavy rain or high humidity. The temperature difference between day and night is large, and condensation occurs at night, which lasts for a long time and has a serious incidence.
3. Prevention methods
a. Collect seeds from disease-free and disease-free plants. Use the seeds within two years, soak them in warm water at 48-49 °C for 30 min, stir while stirring, then transfer to cool water to cool, dry and sown.
b. Implement 2 to 3 years of rotation, apply enough base fertilizer, and timely topdress. Avoid flooding with large water, drain after rain, and protect the ground from ventilation and drainage. c. Spray 75% chlorothalonil WP 600 times solution or 1:0.5:200 Bordeaux solution or 50% sulfur suspension agent 200-300 times solution or lime sulfate copper sulphate powder (30 parts of lime and 10 parts of copper sulphate) , sulfur powder 10 parts), etc., spray every 7 to 10d, a total of 2 to 3 times.
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