Cotton cotton red rot

Symptoms occur in all areas of China's cotton, the Yangtze River Valley, the Yellow River Basin cotton area heavy, Liao River Basin also occurs. Seedlings and bolls can be infected. The infected young shoots were damaged before emergence and the buds turned reddish brown. After unearthed, the roots of the damaged cotton seedlings had yellowed roots and lateral roots, and later turned dark brown and rotted. The infected stem of the young stem becomes dark brown, yellow streak appears at the base of the young shoot near the ground, and it turns brown and rot. The young root and young stem are swollen. The gray color of the cotyledon and the true leaves are irregular. Pink mold layer, which is the conidia of pathogenic bacteria. The early sowing of cotton fields on production or in the event of low temperature and rainy weather caused severe root rot, resulting in dead seedlings. The stems of infected adult stems are infected with ring or local brown scars, cortical erosion, and yellow-brown in the xylem. Cotton boll disease sees boll red rot.

The pathogen Fusarium moniliforme var. intermedium Neish et Leggett called Fusarium spp. intermediate variant; F. semitectum Berk. et Rav. called F. avenaceum (Corde ex Fr.) Sacc. called Fusarium oats, F. Graminearum Schwabe said Fungi such as Fusarium oxysporum are all fungi of the subphylum Subgenie. F. moniliforme var.intermedium is velvet-like, pink, pale purple or rose on PDA medium. Erythrocyte-producing single stem or duplicate bottle stems coexist. Small conidia unit cells, ovate or narrowly melon seed-shaped, strigose or pseudo-headed, size 5.3-10.82.74 (μm).

Transmission routes and disease conditions The pathogenic bacteria overwinters with the diseased body or in the soil. The conidia and mycelium produced by the bacteria become the primary infestation source for the following year. At the beginning of the seedling stage, the infestation source may also be a conidium adhering to the seed fluff and a mycelium latent in the seed, and invade the young shoot or seedling after sowing. The fungus lives in the cotton growing season. Boiling conidia or mycelium spread to cotton bolls by wind, rain, insects and other media, causing rotten bells to invade from wounds, and disease bells make bacteria inside and outside the seeds to form a new infection cycle. Red rot pathogens grow in the temperature range of 3-37 °C, and the optimum temperature is 20-24 °C. High temperature is good for infestation. The incubation period is 3-10 days, and its length varies according to environmental conditions. There is less sunshine, more rainfall, and more rain may cause a pandemic. The occurrence of low temperature and high humidity in the seedling stage is heavier. The boll season is characterized by low temperature, high humidity and high incidence of disease. The cotton plant is greedy for longevity or cotton bolls are affected by pests and diseases, mechanical wounds are more, pathogens are more likely to invade the disease. The dry climate of cotton bolls is dry and the incidence is light.

Control methods (1) Selection of healthy and disease-free cotton seeds. (2) Pay attention to clean the garden, remove pathogens in time, remove the dead branches, fallen leaves, and rotten bells in the field in time, and burn them in a concentrated manner to reduce the initial infection source of the bacteria. (3) appropriate sowing, strengthen seedling management, using formula fertilization technology to promote rapid and robust growth of cotton seedlings, enhance plant resistance to disease. (4) Strengthen the management of cotton fields to prevent and treat pests and diseases in the bolls in a timely manner to avoid causing wounds and reduce the chance of pathogenic infection. (5) Seed treatment. Combine 50% carbendazim WP 1kg per 100kg cotton seed. (6) Prevention of boll period. The first is combined prevention and treatment of other diseases. The second is the timely spraying of 1:1:200-fold Bordeaux fluid or 50% thiophanate-methyl (methyl thiophanate) wettable powder 800 times or 50% carbendazim WP 1000 times, 50% benomyl Ling WP 1500 times, 65% TB wettable powder 1500 times, every 66 square meters spray good liquid 100-125L, every 7-10 days, continuous spray 2-3 times.