Cotton blight
Commonly known as cotton black root disease, rot, root fold disease. The main damage cotton seedlings. Infected stems and stems at the base of the vertical brown stripes, when appropriate conditions quickly spread around the stem one week, shrinking and thinning, stem root rot or root rot. Cotton seedlings lose water faster and generally do not fall flat. Dead seedlings are easily removed from the soil. Sparse filaments and small soil particles adhering to them are visible on the base or on the roots. Infected seeds cause rotten or rotten buds, and the diseased seeds are mostly brown and soft rot. When they are squeezed, yellow-brown mucus flows out. Invasive cotyledons and young leaves form irregular brown necrotic spots and dry perforation. When the humidity is high, sparse white mycelium is visible in the diseased part, and a brown sclerotia adheres to it.
Cotton anthrax
Seedlings and adult plants can be infected. Infected at the seedling stage: The seedlings before germination can cause rotten seedlings; after germination, red-brown longitudinal cracks and strips develop at the base of the stems, and the seedlings are killed due to expansion and contraction. An orange-orange viscous (disease conidia) was developed on the lesions when wet. A round or semi-circular melasma appears on the edge of the cotyledon, and the cotyledon edge is incomplete after drying and shedding.
Cotton red rot
All cotton regions in China have occurred. The Yangtze River valley and the Yellow River basin have suffered heavy damage. The Liaohe River Basin has also occurred. Seedlings and bolls can be infected. Diseases at the seedling stage were damaged before the emergence of buds, and the buds turned reddish brown and decayed. After unearthed, the root tip and lateral roots of the damaged cotton seedlings turned yellow, and later turned dark brown and rotted. Juvenile stem becomes dark brown, and the young stem near the ground shows yellow streak. It turns brown and rot. The young root and young stem are swollen. The cotyledons and true leaves have gray-red irregular spots. Pink moldy layer.
Black root rot of cotton
Seedling stage, adult stage can be disease. The epidermis and the cortex of infected seedling roots become brown after infection, often extending to the hypocotyls, the roots of the roots are swollen, the stems are bent, the plants are short, the lesions of the stems spread, the epidermis is cracked, and the strips or spindles are shallow. The green lesions turn dark purple to black and the diseased plants are easy to pull out, but the vascular bundles do not change color. When the diseased plants became infected, the parietal lobe was drooping, the leaves were pale, and the leaves withered but not exfoliated. The base of the rhizomes swelled, the roots rotted, the stems were bent, and the middle column turned brown to dark purple with little or no bells. Some suddenly lose water and wilt. The last plant died of dryness.
Cotton ringworm disease
Also known as black spot disease. Occurred mainly in 1-2 true leaf stage, injurious to the cotyledons and true leaves. The cotyledon infection is mainly manifested in the cotyledons unfolded bond or the crust damage at the place of the dark green mold layer. The cotyledon was flattened and diseased, with a small round spot of reddish-brown color, and then expanded into an irregular shape to a nearly circular brown spot, and some had unobtrusive ring veins. When the humidity is high, the dark green mold layer grows on the lesions, and the number of lesions on each of the severe leaves is as large as several tens, resulting in the cotyledons off-focus. Symptoms of true leaf disease are similar to those on the cotyledon, but the lesions are large and there are purple-red lesions around. Injury occurred when the disease, the shape of the lesion is irregular, there are no purple edges around the spots. The infection of the stem or petiole of the seedlings is mainly the production of oblong brown concave spots, causing the leaves to fall and the seedlings to die.
Control methods
(1) Use good-quality, disease-free seeds and seed treatment before sowing. Seed treatment can be used with Likang seed dressing.
(2) appropriate sowing, nurturing strong seedlings, promote the early development of cotton seedlings, and improve disease resistance. Chemical control: 1 with Likang 3000-4000 times liquid to root; 2 Fujin 700-800 times liquid irrigation or foliar spray; 3 Likang 600-800 times liquid irrigation or foliar spray; 4 Likang and vegetables Dedicated foliar fertilizer 300-500 times liquid foliar spray; 5 Likang 1000-1500 times liquid foliar spray or irrigation root. 6 basic copper sulfate 500-800 times spray. 750% brominated isocyanuric acid 1200-1500 times spray.
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