Symptoms and causes of melon disease

I. Symptoms: The base or middle part of the embryo stem exposed at the seedling stage is water-soaked, and then turns into a yellow-brown dry and shrunk into a linear shape. The cotyledons are not yet wilted, and the seedlings suddenly collapse, causing the seedlings to stick to the ground, sometimes The hypocotyls and cotyledons unearthed from the melon seedlings have been generally rotted and browned. When the humidity is high, white cotton-like hyphae grow near the diseased plant. The fungus infects the fruit and causes cotton rot. At the beginning of the water-stained spots, it quickly expanded into a yellow-brown water-stained large lesion, which was obvious with the health part. Finally, the whole fruit rotted, and a layer of white cotton-like hyphae grew outside the diseased melon. The onset of fruit begins in the umbilicus, and some invade from the wound and begin to rot in the vicinity. Linyi Fertilizer Network Copyright

Linyi Fertilizer Network Copyright

Second, the disease factors: the pathogens use the oospores to stagnate the mycelium (spore sac) in the soil, infesting the melon seedlings to cause tripping. Reinfection in the field mainly relies on sporangia and zoospores on the seedlings, causing more serious losses by splashing irrigation water or rainwater on the roots or fruits close to the ground. The pathogen growth temperature is 15~16°C, and the temperature is higher than 30°C. The suitable temperature is 10°C. The low temperature is not good for host growth, but the bacteria can still move, especially the low temperature and high humidity conditions during the seedling stage, which is conducive to the onset. When the nutrients of the seedlings are basically used up, the new roots are not susceptible until they are ill. At this time, the true leaves have not been extracted, the carbohydrates can not be increased rapidly, the disease resistance is weak, in case of rain, snow, cloudy or cold, the ground temperature is low, the photosynthesis is weak, the melon seedlings have enhanced respiration, the consumption is increased, and the young stems are caused. The cells are elongated, and the cell wall is thinned and the bacteria invade. Therefore, the disease mainly occurs when the seedling grows 1 or 2 true leaves, and after 3 true leaves, the incidence is less. As a result, the rainy days and the fruits are susceptible to disease. Linyi Fertilizer Network Copyright

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