Common Diseases and Control techniques of Cotton

First, blight

Cotton blight, commonly known as root rot disease and black root disease, occurs in all cotton areas throughout the country. after the damage of cotton seedlings, yellow-brown disease spots are produced at the base of the stem near the ground, and then become dark brown, and gradually sunken and rot, and in serious cases, the disease becomes thinner, and the diseased seedlings wither or wither. After the cotyledons were damaged, irregular yellowish-brown spots were formed, and then the disease part was broken and fell off into a perforated shape. After the damage in the adult stage, brown spots appeared on the leaves, and then shedding and perforation.

Control methods: 1. Reasonable rotation: with Gramineae crops: rotation for more than 2-3 years. 2. Rational fertilization: fine soil preparation, increasing the application of rotten organic fertilizer or 5406 bacterial fertilizer. 3. To improve the sowing quality: the suitable sowing time for spring cotton is 5 cm deep and 14 ℃, and the general sowing time is 4 cm deep and 5 cm deep. 4. Strengthen the management of seedling stage: properly early seedling and diligent ploughing, reduce soil moisture, increase upper temperature and cultivate strong seedlings. 5. Dressing selected seeds with medicament. Mix seeds with 50% carbendazim of 0.5% to 0.8% seed weight or 50% methyl topiramate of 0.6% seed weight.

2. Fusarium wilt

Fusarium wilt, also known as plant cancer, is the enemy of cotton production and has spread rapidly in recent years. Fusarium wilt is characterized by dwarf plant, gray-green leaves, brittle and hard stem, bent stem, shortened stem knot, sunken center, and grayish brown or light black vascular bundles in the stem. Disease conditions: high temperature and humidity, continuous stubble planting, sunny day after rain, will be a line, into pieces of death.

Control methods: 1. Soil improvement: on the basis of applying organic fertilizer, nitrogen, phosphorus and potassium, 0.5 kg heavy stubble agent per mu is applied and then ploughed, which can kill most of the bacteria in the soil and increase the air permeability in the soil. eliminate the content of sulfite in the soil, break the consolidation, improve the saline-alkali, enhance the plant disease resistance, and reduce the harm of Fusarium wilt. 2. Apply appropriate amount of nitrogen fertilizer. 3. Timely watering, cotton has an average of two bolls per plant when the weather is dry, watering the first water early will promote the occurrence of diseases; 4, seedling stage, bud stage and flower and boll stage regularly spraying 24 times of first aid, or carbendazim to control Verticillium wilt. 5. The diseased plants can be prevented and treated by operation. A knife is used to cut the vertical mouth of 2cm to 3cm on the stem at the base of cotton, and two sections of matchsticks soaked in yellowing first aid solution for more than 4 hours are inserted. The above methods can effectively control the harm of Fusarium wilt of cotton, and can also prevent and control the wilt of other crops.

III. Black rot

Black rot cotton root epidermis is black, slightly raised, no new roots grow, the plant is short, the leaves are soft, the growth is slow, it is easy to die under high temperature, after death, the plant is black blight, upright, and the disease area is massive. The land with long stagnant water after rain, low-lying terrain, heavy saline-alkali or large amount of nitrogen fertilizer was not ploughed in time, and sweet potato, sugar beet, Chinese cabbage, cabbage and radish planted in the previous crop were prone to this disease.

Prevention and control methods: 1, leveling the land, prevent stagnant water, timely drainage. 2. Ploughing and loosening the soil in time after rain to improve the root activity. 3. Adding 15 kg of lime powder per mu, 10 kg of ferrous sulfate or heavy stubble agent and Feilibao can reduce and control the occurrence of the disease. 4. Increase the application of organic fertilizer and phosphorus and potassium fertilizer, control and apply appropriate amount of nitrogen fertilizer; 5, use withered yellow first aid during the disease period, 20 grams of rotten Sukang, adding 15 kg of water, spraying foliar or root irrigation can effectively control black rot.

IV. Virus disease

Cotton virus disease mainly includes lobular virus disease, mosaic virus disease, curl wilt disease, purple leaf virus disease, fallen leaves, falling flowers, fruit drop virus disease, virus disease known as plant AIDS, spread quickly, serious harm, reduced production in the invisible, is the first enemy of plants.

Prevention and control methods: in the early stage of cotton growth, it can be prevented by virus doctor, antitoxin, virus killing and withering.

5. Stem blight

Cotton can be damaged from seedling stage to boll setting stage, and the early stage is harmful to cotyledons, true leaves, stems and growing points, resulting in rotten seeds, leaf spots, stem withering, decapitation and even the death of the whole plant, and infects bracts and green bolls in the later stage, causing deciduous leaves and stiff leaves. Cotyledons and real leaves are yellow-brown small round spots at the beginning, the edges are purplish red, and then expand into nearly round or irregular brown spots, with many small black spots (pathogens) scattered on the surface. The stem and petiole were damaged, initially as reddish-brown dots, and then expanded into dark brown fusiform ulcer spots, sunken in the center, and purplish red around. When the disease is serious, the disease part breaks and falls off, and the stems and branches die.

Prevention and control methods: 1, reasonable rotation, reasonable close planting, improve ventilation and light transmission conditions. 2. Seed dressing, after sulfuric acid de-velveting of cottonseed, mixed with seed coating agent with the ratio of carbofuran and carbendazim (1: 0.5), it can prevent disease and treat aphids as well. 3, spray, seedling stage or adult stage disease, you can use 65% Dysen zinc 800x solution, or 70% methyl topiramate 1000 times solution spray control.