Diseases and Prevention of Transgenic Cotton

The popularization and popularization of transgenic insect-resistant cotton has effectively controlled the damage of lepidopteran pests such as cotton bollworm and red bollworm, and has achieved good economic, ecological and social benefits. However, due to its special growth and development characteristics, the currently popular resistance to insect-resistant cotton is generally not strong. The disease characteristics, etiology and control techniques are described as follows, aiming to provide services for high-yield and high-quality cultivation of large-scale insect-resistant cotton.

First, the characteristics of the disease and the cause of the disease

1. Severe disease at seedling stage. The cause of the disease is: (1) Variety characteristics. Most of the transgenic insect-resistant cotton grow slowly in the seedling stage, has a small amount of growth and is weak in disease resistance, especially the introduction of the American Cotton 33B as the center. (2) Seed quality. The insect-resistant cotton seed market has a large demand and the price is high. Some seed production enterprises blindly pursue the seed production in order to earn high profits, the seeds are not strict, and shoddy, resulting in poor quality and viability of some production seeds. Low, seedling growth is weak and disease resistance is poor. (3) sowing quality. Seeding is too early and the ground temperature is low; sowing is too deep or too shallow; lyrics are insufficient or the humidity is too high during sowing; lax filming, etc. can cause low seedling emergence, thin seedlings, and severe disease at the seedling stage. (4) Environmental conditions. Seedling rain is more humid, and when the temperature is low, the disease is serious. From 2002 to 2003, due to this reason, the seedling stage disease in the cotton fields of the Yellow River Basin occurred seriously, mainly due to the complex root disease mainly caused by blight, and many cotton seedlings died from cavities.

2. Verticillium wilt epidemic occurs. The cause of the disease is: (1) Variety characteristics. The currently popularized transgenic cotton varieties have poor resistance to Verticillium wilt. Among the certified varieties, susceptible varieties accounted for 64.3% and no resistant varieties. (2) Planting methods. The serious cotton crops that do not pay attention to crop rotation are serious. (3) Environmental conditions. Low temperature and rain easily lead to the epidemic. In June 2002 and June-July 2003, Verticillium wilt occurred in many areas of the Yellow River Basin due to the continuous and rainy low temperatures. In many areas, the incidence rate is as high as 70-80%, and some susceptible varieties fall into light poles and the rate of diseased plants exceeds 50%.

3, severe physiological premature aging. Premature aging is a non-invasive disease that is a physiological disease that is widespread in insect-resistant cotton. Generally began to show in mid-September, the leaves turn green and turn red, yellow and a large number of shedding; the upper fruit branches are short, the flower bell is weak, fall off, and in severe cases only the cotton stalks and bolls or blue and dry. According to reports, the reduction in light production caused by premature aging is as much as 10-20%, and the weight is 30-50%, and the fiber quality is greatly reduced. The cause of the disease is: (1) Variety characteristics. The transgenic insect-resistant cotton is generally developed earlier. The vegetative body has not yet fully developed and rapidly begins reproductive growth. The vegetative body is thin, affecting its absorption of fertilizer, water, and light; the transgenic insect-resistant cotton needs a large amount of fertilizer and is sensitive to potash, lacking. It is easy to cause premature aging. In addition, the insect-resistant cotton has a fast growth in the middle period, and has a fast speed of bell-ringing and more nutrients, while nutrient absorption and photosynthetic production can not keep up, and the leaves and roots are not well developed. (2) fertilizer and water management. Farmers often have insufficient fertilizers in crop cultivation and neglect the use of organic fertilizers and phosphorus and potassium fertilizers; flower bell fertilizers are applied late, and do not pay attention to top-dressing fertilizers and late-stage foliar fertilizers; droughts do not (can) timely irrigation, When stains do not (can) timely drainage. (3) Cotton bolls structure. Transgenic insect-resistant cotton buds early and later buds. Farmers believe that as soon as possible, as soon as possible, more and better, and do not take measures to manage, let it be allowed to go, resulting in a large number of pre-fat peach, late autumn peach, a large proportion, and better quality of the peach, early autumn peach so affected The number decreases and the proportion decreases. Fuchs peaches and late autumn peaches are of poor quality and have little contribution to yield, and their presence causes the growth and development of cotton plants to be unbalanced. (4) Environmental conditions. Prolonged drought or prolonged rain; prone to rain and late drought can affect root development.

4, prone to leaf blight. There are many causes of the disease, which are mainly related to soil, fertilizer, water, climate, and cultivation management. Insufficient potash fertilizer and organic fertilizer are scarce, and continuous cropping is more serious. The transgenic insect-resistant cotton needs large amount of potassium and is sensitive to potash fertilizer. Farmers have consistently ignored the application of potash fertilizer in crop cultivation and the organic fertilizer application amount is insufficient. Therefore, the disease is more likely to occur on transgenic insect-resistant cotton.

Second, the prevention and treatment of transgenic insect-resistant cotton diseases

Comprehensive analysis of the causes of each disease can prevent and control the occurrence of each disease from the following aspects.

1, improve the quality of seeds. All seed production enterprises should strictly control the production and processing of seed quality, ensure the quality of seeds, and establish a strong seedling foundation.

2, choose a good species. In the production, the transgenic insect-resistant cotton varieties with strong growth vigor at the seedling stage and good resistance to resistance to Verticillium wilt are preferred for domestic breeding, such as Zhongmian 29, Zhongmian 38, and Luken Cotton Series. Variety.

3, ridge cultivation, crop rotation. Rigid cultivation facilitates irrigation and drainage, and ventilation and light transmission in the field are also good. Reasonably carry out crop rotation, especially plots infected with verticillium wilt, need to rotate with cereal crops for 3-4 years.

4, Shizujifei, scientific fertilizer. According to the characteristics of large amount of fertilizer, early flowering and ringing, and sensitive to potash fertilizer, the transgenic insect-resistant cotton should follow the principle of “enriched base fertilizer, increased application of phosphorus and potassium fertilizers, increase the amount and proportion of potash fertilizer, and pay attention to top dressing and top dressing. In the later stage, the principle of top-dressing the leaves and top dressing is 8-10 days earlier than conventional cotton. Apply basal fertilizer before sowing and plough the land. 2000-2500 kg of fertilizer per acre, 50-70 kg of cottonseed cake, 10-15 kg of urea, 20-30 kg of diammonium phosphate, 25-30 kg of potassium chloride or potassium sulfate, 1 kg of zinc sulfate, 0.75- 1 kg base fertilizer. Around June 10, Mushi urea 4-5 kilograms of buds grow. In late June, combined soil fertilization and boll fertilizer, topdressing 15-20 kg urea per mu, 15 kg of diammonium phosphate. In late July, top dressing fertilizer was applied, and urea was applied at 10-15 kg per acre. For fields with premature aging or red stem blight, extra-root fertilizers can be applied. Fertilizer concentration was 1% urea, 0.4% potassium dihydrogen phosphate, and the ratio was 50 kg of water plus 0.5 kg of urea and 0.2 kg of potassium dihydrogen phosphate. Every 7-10 days, a total of 3-4 sprays.

5, appropriate film sowing, improve the quality of sowing. The safe planting period for film-covered sowing in the cotton-growing areas of the Yellow River Basin was after April 15th. During the planting time, the weather of “cold-tail warmer” was selected. Sowing depth 2-3 cm, planting enough to improve the quality of the film. Immediately after the seedlings were broken and the seedlings were released, and the membrane opening was severely sealed.

6, strengthen seedling management, promote Miaowang long hair. After spraying, Bordeaux or Thiophanate-methyl and other liquids are used to prevent (control) the occurrence of seedling disease. Several times are sprayed when the temperature is low for a long time and the rain is continuous; irrigation is performed with agents such as fulvic acid and root disease. Roots, once every 7 days, 3-4 times in a row can effectively control the occurrence of Verticillium wilt; seedling spray green wind 95, Tianwei and other regulators to promote seedlings grow strong, increase resistance to disease.

7, full control. At the seedling stage, green wind 95, Tianwei, etc. are used to promote long-term growth of the seedlings. In the middle growth stage, the growth is controlled by the use of Dianchimine, which is usually sprayed once before and after the first flowering stage, flowering stage, and August 5th.

8, remove the early and late buds. Removing early and late buds can reduce the ineffective consumption of nutrients, coordinate vegetative growth and reproductive growth, effectively prevent premature aging, and facilitate high yield and quality. The removal of early buds was generally performed in the middle or late June. Each of the plants removed 6-8 early buds or removed the lower two buds. The removal of late buds can be done by removing the middle and lower fruit branches or chemically capping methamphetamine. These two methods can be performed before and after August 5th.

In addition, timely cultivating and earth-cultivation, timely peeling off the film to promote the development of the root system; timely irrigation and drainage, irrigation during the flowering and boll-opening period, and dredging the drainage canal in the event of flooding; .