Cotton withered and Verticillium wilt is a worldwide dangerous disease, and it is an international phytosanitary target. The country's cotton regions are light and heavy, and are becoming increasingly serious, becoming one of the main factors affecting cotton growth. Cotton withering and Verticillium wilt is known as the cancer of cotton. At present, there is no effective chemical control in Daejeon. Therefore, it is particularly important to rely on appropriate cultivation and management measures to reduce the incidence of cotton blight and verticillium wilt in cotton fields; on the contrary, improper management can induce massive occurrence of cotton blight and verticillium wilt in cotton fields. The common improper cultivation and management that can induce dry and yellow wilt diseases can be summarized as follows:
First, improper herbicide application. In order to eradicate weeds in the field, the herbicide application rate is much higher than the normal amount, which means that the greater the amount, the better the control effect. As everyone knows, the excessive use of drugs has also greatly affected the normal growth of cotton, cotton growth is slow, and disease resistance is reduced. This cotton field often shows symptoms of dwarfing blight. In addition, when herbicides were applied before cotton seedlings were extirpated, the herbicides were sprayed on the mulching film. As a result, the herbicides on the mulching film after seedlings were easy to injure the cotton seedlings and cause dead seedlings, which was considered as a blight by people. Of course, if excessive herbicides are applied to the management of crops from the Shangyu crops, the pesticide residues will also have a greater impact on the growth of cotton, which will easily lead to disease. This is one of the main reasons why the disease is aggravated despite the rotation.
Second, year after year of ploughing without deep turning soil tillage. Deep plowing before winter is not only conducive to the accumulation of winter and spring snow and rain, lifting and protecting soil, but also conducive to drying ridges to kill the soil of the bacteria, to prevent the occurrence of dry, yellow wilt disease. Years of rotary tillage caused the cultivating layer of the cotton field to be too shallow, the bacteria accumulated in the soil at a depth of 10-15 cm, the granular structure of the soil was destroyed, the soil quality deteriorated, the root system could not be lowered, and the cotton plant was susceptible to disease. The depth of arable land before winter is better than 25-30 cm.
Third, flood irrigation. Cotton blight and verticillium wilt, as a malignant disease, can easily spread with flooding, resulting in spotting. Therefore, when cotton is sowed before sowing, it is necessary to adopt furrow irrigation, so that water saving and energy saving are conducive to conservation and can prevent the spread of germs along with the spread of large areas of water.
Fourth, improper fertilization. Balanced fertilization and multiple application of organic manure are one of the effective measures to reduce field diseases. Nitrogen, phosphorus and potassium fertilizers should be mixed in a ratio of 3:1:4. The single application of nitrogen fertilizer is more severe, and potassium deficiency will affect the absorption of nitrogen and phosphate fertilizers. At the same time, it will make the disease worse. Nitrogen fertilizer is applied in some areas, and potassium deficiency is a common phenomenon. Most cotton fields have not applied manure for many years, and other organic fertilizers are even less.
Fifth, sowing discomfort. Timely sowing and appropriate sowing depth are critical for the prevention and treatment of a large number of diseases. Early sowing and too thick overburden can aggravate the disease. The reason is that the sowing is too early and the temperature is too low to cause the seeds to germinate quickly; the seeds are too thick and the soil is too thick and the unfavorable seedlings are quickly unearthed, even if they emerge, they are also weak seedlings. At this stage, the possibility of pathogenic bacteria infestation is great; therefore, the faster the emergence, the lighter the incidence. The correct course of action is to create favorable conditions for the seed to germinate as soon as possible, and to appropriately postpone the sowing of the diseased land and properly broadcast it.
Sixth, the seedlings are not timely. Some people are accustomed to wait until the cotton seedlings are almost fully discharged before they are released. The risk of doing so is extremely high. In case of rain during the seedling stage, the disease will be aggravated. At this time, the cotton seedlings will grow under the membrane and the disease will increase. The correct approach is to release the seedlings in a timely manner. Do not wait until the cotton seedlings are fully discharged. Which seedlings can be put on. If there is rain, try to hold the seedlings as soon as possible. Do not delay and delay the day and the disease will increase.
Seven, the cultivator is not timely after the rain. Studies have shown that: After the rain in the cotton field, high humidity, low ground temperature, soil compaction is very conducive to bacterial infection; so after the rain should be timely cultivator to remove the compaction, loose wet warming.
Eight, control is not in place. Chemical control is through the use of growth regulators to control individual fertility, making it in the direction of people's expectations, to ensure the development of key organs and functional expression. The pre-management focus is to “promote rootsâ€, increase the number of leaf resources on the basis of promoting roots, and establish a high-yield shelf to increase crop productivity and improve quality. Studies have shown that chemical control can effectively reduce disease.
Therefore, we must base our efforts on comprehensive prevention (including the selection of disease-resistant varieties, rotation of crops, removal of diseased plants, removal of cottonwood and weeds, etc.), mobilization of all means, and the creation of a disease that is not suitable for the infestation of pathogens to facilitate the robust growth of cotton plants. surroundings. In short, any measures that are conducive to cotton seedlings promoting roots and strong trees can effectively prevent and reduce disease.
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