Cotton withered and Verticillium wilt is a devastating disease in cotton production. Cotton farmers are known as the "cancer" of cotton. They have the characteristics of rapid spread, serious losses, and difficulty in control. In recent years, in China's cotton district, the damage has been increasing year by year, and the prevention and treatment of the work is a matter of no delay. According to the reporter’s recent understanding, the main causes of the heavy damage caused by the wilt disease of cotton are as follows: First, the seeds were randomly introduced and quarantined; quarantine-free introduction of disease-free zones from the wards resulted in the rapid spread of disease. The important way to spread. Second, the varieties of insect-resistant cotton currently planted have reduced resistance to disease due to the introduction of insect-resistant genes. Most of the insect-resistant cotton varieties are resistant to wilt disease and not resistant to verticillium wilt, usually only with resistance to wilt and verticillium wilt resistance. The variety is available for selection. Third, the bacteria live in the soil for a long period of time. With the extension of the cultivation period, the bacteria gradually accumulate in the soil, leading to an increase in the disease year by year. Fourth, prevention and control work can not keep up. Most cotton farmers do not pay attention to quarantine and sporadic disease prevention and control, neglecting seed disinfection, crop rotation change, and other cost-effective prevention and control measures. Once the disease occurs in a large area, it will be difficult to prevent and control. . In particular, this year, the area under cotton cultivation has been reduced. To increase the yield of cotton, how to prevent the yellowing and wilt disease, farmers are very anxious and are eager to learn about effective prevention and control measures. In order to help farmers correct the control of the browning and wilt disease, the reporter recently interviewed a cotton expert and Jia Dengsan, senior agronomist of Shandong Changle Agricultural Bureau.
"For cotton withered and verticillium wilt, it must be based on prevention. Control measures must be adapted to local conditions. It is advisable to receive it sooner rather than later so as to obtain better results." Jia Dengsan made a point and said clearly. How do you do prevention and prevent and control measures to suit your local conditions? Jarden III lists the following points:
First of all, it is necessary to do a good job of quarantine protection. Quarantine in disease-free areas is an effective preventive measure. Due to the rapid spread of cotton, Verticillium wilt, serious losses, and difficulty in control, it is a dangerous disease that has caused serious damage to China's cotton production and is still listed as an important quarantine subject. On the basis of a successful screening of diseases, the wards and non-disease areas shall be divided and the plant quarantine system shall be strictly implemented. When planting, the allocation of seeds and quarantine procedures must be performed. Elimination of disease transmission in the acquisition, ginning, processing and other channels. The cotton seed in the ward must first be disinfected and tested in the isolation zone for one year to prove that there is no pathogen before it can be planted in a disease-free area.
Secondly, we must eradicate sporadic diseases and control the spread of diseases in sporadic wards. We must take measures to eradicate the disease, use comprehensive measures such as crop rotation, seed disinfection, and replacement of improved varieties to effectively control the spread of disease and eradicate the disease in the embryonic stage. . The so-called sporadic disease indicates that the diseased rate in the field is below 0.1%. At this time, the germs are in an unstable state, scattered and isolated, and the accumulation of bacteria is still small. This is a good time for easy eradication. The method of eradicating diseases is: after the emergence of cotton to flowering period, regular field investigations are conducted. The diseased plants are found to be properly marked, and after the diseased plants are removed, the soil within one square meter of the diseased plants is immediately completely disinfected, and the diseased bacteria are completely eliminated. Kill. Per square meter of disease, irrigation 90% chloropicrin 360-fold dilution 45 kg, after the liquid infiltration with dry soil coverage. Or within the disease point per square meter, use 90 grams of 90% cotton wadding wettable powder, evenly mix in the soil of the sick spot, water 15~25 kilograms to infiltrate the mixed medicinal soil layer, and then cover dry soil and seal tightly.
The third option is to use land plots that are resistant to disease-resistant varieties, adopt comprehensive control measures based on the selection of disease-resistant varieties, and use disease-resistant varieties as the most economical and effective control method. At present, there are many varieties of anti-fusarium that can be selected for production in China. In a single area of ​​wilt disease, it can fully meet the needs. However, in areas where there is a mixture of blight and verticillium wilt, it is necessary to use varieties with both resistance to blight and verticillium wilt; while there are few varieties with high resistance to verticillium wilt, and the yield and quality are also not ideal, usually only with resistance to wilt Varieties resistant to Verticillium wilt are available. Can be adapted to local conditions Lumianyan 15, No. 20, No. 31, No. 24, Han cotton 616, No. 8 and other varieties of cotton.
The fourth is to implement crop rotation and control crops to harm long-term continuous cropping of cotton. Not only does it reduce the soil fertility, it affects the growth and development of cotton, weakens the resistance to diseases, and it also affects soil diseases, especially for the blight and verticillium wilt belonging to the soil habitual bacteria. It will cause continuous breeding and accumulation, which will increase the disease year by year. After the crop rotation, due to the change of the host crops, the breeding and accumulation of diseased parasites will be disturbed. After a certain period of time, the pathogens will gradually decrease or disappear. In addition, the rotation can also regulate the changes of the soil microbial community, and promote the enhancement of microbial activity that has a causative effect on pathogens, thus inhibiting the growth of pathogens. Here he gave an example: In the heavy-illness fields of cotton withering and verticillium wilt in Liuzhuangcun, Xinxiang County, Henan Province, after four years of wheat and corn replanting, the incidence of Fusarium and Verticillium wilt dropped below 1%.
In addition to the above four measures, Jia Dengsan also emphasized that the control of blight, seed disinfection is essential, because the seed disinfection is more than one. For germ-borne seeds, a disinfection measure is adopted to eliminate dozens of pathogenic bacteria on the seeds at one stroke. This will prevent transmission and spread of cotton seed with Verticillium dahliae and Verticillium dahliae in order to ensure that cotton seedlings will not be harmed by pathogens borne by the seeds. Reduce the pathogenic bacteria Boll bacteria have a good effect. There are many ways to disinfect seeds, and the commonly used method is soaking in carbendazim suspensions. Dispose 100 kg of 0.3% carbendazim suspension concentrate solution, use 99.25 kg of fresh water, add 40% carbendazim gel suspension 0.75 kg, mix well, then add 40 kg of wool and cottonseed, soak for 14 hours at room temperature , turn the middle 2 to 3 times. The liquid can be soaked 2~3 times continuously without affecting the disinfection effect. The 40% carbendazim suspension is also suitable for the disinfection of the soil in the nursery of cotton. It can achieve the purpose of disinfection by the same dosage and the same method of use, and is more effective than the eradication of sporadic diseases. Cost-effective.
Finally, Jia Dengsan reminded the cotton farmers that there is a certain effect on the prevention and treatment of mild disease. It is necessary to conduct field investigations in time and spray the plants with anti-blow and yellow mildew, or hymexazol, or ibretidine 2 to 4 Secondly, there is the effect of controlling the spread of diseases and reducing the hazards. At the same time as the spraying, the root canal treatment with one of the above-mentioned drugs within the range of one square meter of the diseased bacterium can significantly improve the effect of the spray. Spraying with watering and raining can increase control effectiveness.
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