Due to the continuous rainwater during the planting of cotton and after its emergence, this year's dead seedlings are more serious than in previous years, and the most serious ones have begun to be destroyed.
First, the main symptoms
After the cotton seedlings have been unearthed, the base of the stem (and the place where the ground meets) appears yellow-brown lesions, which gradually protects them from depression and rot. The color turns black and brown, and the cotton seedlings die. This is a typical “setbackâ€, which is commonly known as cotton farmers. The "black neck" disease.
Second, the cause of death
1. The sowing date is early and the temperature is low. According to the forecast of the meteorological department, the temperature in April 2008 was 3~5°C lower than average in previous years. Most cotton farmers did not postpone the sowing date according to the temperature, and even the sowing date was advanced, causing the emergence of cotton to be slow and the infection time of the bacteria. Long, heavy onset.
2. Rain and humidity. The resistance was the weakest within 15 days after the emergence of cotton seedlings, and severe cases of low temperature and high humidity seedling disease occurred. Starting from late April this year, the rain continues, cotton seedlings are almost soaked in rain, and the root system cannot breathe. Humidity is too high, resulting in the occurrence of serious disease, cotton seedlings die, low-lying, poor drainage and soil viscosity of the cotton field is the most serious.
3. Severely severe. Since most of the cotton in our province is planted year after year, the number of pathogenic bacteria in the ground has accumulated too much and the number of beneficial bacteria has been too small, resulting in heavier disease.
4. The quality of cotton seed coating agent does not matter. Many kinds of sub-coating agents are written with insect-resistant and disease-resistant, but cotton seedlings are not resistant to disease or insects, and pests and diseases occur.
Third, control methods
1. Seed treatment. When replanting, deforestation, or sowing of cotton and summer sowing of cotton is required, due to the current low temperature and high humidity, we must do a good job of preventing disease. Can be used before sowing with high Qiao 10 milliliters and beneficial micro-bacterial agent 50 grams mixed with 1.5 kilograms of cotton seed, the seed treatment or secondary coating, can effectively control the disease of double crops, make cotton seedling thick, the incidence of disease control in the Below 10%, no ticks are produced for 50-60 days.
2. Agricultural control. After the rain is fine, we must take measures to remove roots from the cotton seedlings, reduce the humidity of the roots of the cotton seedlings, increase the temperature of the ground, and reduce the occurrence of diseases. In areas with too much rain, it is recommended to take measures such as removing the film, removing moisture, and keeping the seedlings after sunny weather.
3. Chemical control. For the onset and severe incidence of cotton fields, spray the roots and stems promptly. The better effective agents are Rui Miao Qing 2000 times liquid + beneficial micro bacteria 500 times liquid or Rui Miao Qing 2000 times liquid + Bi Hu 10000 times liquid, which can effectively control the dead seedling phenomenon.
4. Timely treatment of worms. The use of long-acting agents to control aphids, such as 600 times the current good year or 3000 to 6000 music, can reach the validity period of more than 20 days.
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