The seedling stage of cotton is very important, which directly affects the future harvest. Especially in the seedling stage, it is necessary to pay attention to the prevention and control of diseases. Rainy days are especially important. Next, Xiaobian will summarize how to prevent and cure diseases during the cotton seedling period in the rainy days.
First, the symptoms of cotton seedlings in the rainy days:
1. Cotton blight. The cotton seedlings were killed before they were unearthed, causing rotten seeds and rotten buds. After the seedlings were unearthed, the spots on the base of the young stems close to the ground appeared yellowish brown, and the lesions that turned black were gradually enlarged, surrounding the entire base of the stem, and eventually the seedlings died. Pulling up the diseased seedlings, it is obvious that the diseased part and the surrounding soil often have hyphae. Cotyledons are damaged, and irregular yellow-brown lesions appear in the middle.
2. Cotton anthracnose. Cotton seedlings can be seen before they are unearthed, and hypocotyls and young roots turn brown and rot. The seedlings of unearthed cotton seedlings have reddish-brown small spots at the base of the stem, and the fusiform streaks with purple-brown depressions are enlarged, and the lower limit of the longitudinal slits is often contracted around the waist. In humid conditions, the lesion can develop in depth and reach the top of the young stem to form a top rot. After the root is infested, it is dark brown and semi-wet and rot. After being pulled up, the cortex is not easy to break, which is different from the blight. The incidence of cotyledons is mostly semi-circular pale brown to brown lesions on the leaf margin, and the edges are reddish brown; in wet weather, the surface of the lesions produces orange-red sticky spores.
3, cotton red rot disease. The cotton seedlings were damaged before they were unearthed, and the young shoots turned yellow brown and rot. The roots of the unearthed cotton seedlings were damaged, and the root tip first turned pale yellow, then browned and rotted, and gradually spread throughout the roots. The young stem base is damaged, first turned yellowish brown, then turned dark brown and rot, and the lesions are not sunken. The main stems and the tender stems of the ground become coarse and produce brown short streaks, which is the main feature of the disease. Cotyledons are damaged, and more gray-red irregular or nearly round lesions are produced at the edges. The lesions often rupture, and the pink part of the disease is produced in the diseased part.
4, cotton collapsed. The main symptoms are that the seedlings are light brown from the base and soften and fall down. The cotyledons are also softened and stained with water stains. The disease develops rapidly, so it is called squatting. Most of the pathogens first invade from young and fine roots and extend to young stems and whole seedlings. When the soil moisture is high, the seeds and newly germinated sprouts can also be infected, affecting emergence or forming weak seedlings. White fine flocs are sometimes seen on the fallen dead seedlings.
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