Control measures for rice seedling disease

The rice seedling disease is famous for its long illness and the public rice. The disease is distributed in various rice regions of the world, and occurs in all rice regions of China. The disease can be basically controlled by the seed disinfection and the use of disease-free seeds.

First, the symptoms

It can occur from the seedling stage to the heading stage. Seed-borne bacteria are the main cause of the onset of seedlings. Seriously ill seeds often fail to germinate, or seedlings after germination can die soon. It is common for plants to grow up. The onset of seedling stage is related to grain-borne bacteria. The diseased seedlings grow light and high, 1/3 higher than the healthy seedlings, the leaves are narrow and long, the whole plant is yellowish, the root hair is sparse, the roots are poorly developed, and some are dead. There is a reddish or white powdery mildew on the seedlings. In the adult stage or about 1 month after transplanting, the diseased plants appear in the same way as the seedling stage. The tiller is less or not divided, the internodes are obviously elongated, the internodes are curved to expose the sheath, and the lower stems give birth to many inverted adventitious roots. . Cut the diseased stem and see the white spider filament disease. Severely ill plants usually die at the booting stage, and the lightly diseased plants often have early heading, and the ear shape is short or the grain is not real. When the weather is wet, the surface of the dead plant is covered with light red or white mildew.

Second, the incidence factor

The occurrence of the disease has a great relationship with soil temperature. When the soil temperature is 30-35 °C, the seedlings appear most, and at 25 °C, the seedlings appear less, and the 20 °C diseased seedlings do not show symptoms. Different varieties of rice have different disease resistance to the disease, but there is no immune variety. The wound is conducive to the invasion of germs, and the seeds that are injured during threshing or the seedlings that are injured during transplanting are susceptible to disease. When the seedlings are nursed, the seedbed irrigation is not timely. The water shortage is cracked by drought, and the roots of the seedlings are easily injured. When the seedlings are pulled out, the roots are injured due to lack of water on the nursery bed. This kind of seedlings is seriously affected after transplanting. Seeds that are incompletely sterilized by chemical soaking seeds are more serious than those that are thoroughly immersed in seeds.

Third, prevention measures

This disease is a small circulation disease dominated by seed transmission. Therefore, the establishment of disease-free seeding, the selection of disease-free seeds and seed treatment is the key to prevention.

1. Establish disease-free seeding fields: disease-free seeds should be used for planting and seed disinfection treatment should be carried out. After planting the fields and the general production fields nearby, it is found that the diseased plants or diseased plants should be removed in time to prevent spread. Keeping the farm should be single, single, and single.

2, seed disinfection treatment: seed disinfection treatment is an effective measure to prevent this disease. Commonly used agents and methods for seed disinfection are:

(1) 25% Shi Baoke (prochloraz) emulsifiable concentrate 25 ml, add 0.15% natural alizarin 20 ml, add 100 liters of water to mix, can soak 100 kg of rice seeds, temperature 10-15 ° C, soaking seeds 7-5 Day, temperature 16-20 ° C, soaking seeds for 3-4 days, temperature 20-25 ° C, soaking seeds for 2-3 days, and stirring three times a day, take out direct germination.

(2) 25% soaked the 2,000 times solution of 100 grams of emulsifiable concentrate for 72 hours, which can also prevent the disease and prevent rice blast.

Generally, the water level of the soaking seeds should exceed 10 cm of the seeds and be stirred once a day in the morning, in the middle and in the evening.
3, the removal of diseased plants: combined with field operations, found that the diseased plants should be immediately removed from the roots to prevent spread.

4. Prevent rice roots and seeds from being injured: Preventing wound formation is the key to reducing the invasion of germs. For example, during the nursery period, it is necessary to prevent water shortage and drought, and damage the rice roots; before planting, the water should be moistened first to prevent damage to the roots of the seedlings; when the grain is removed, the gap of the threshing machine should not be too small, and the rotation speed should not be too fast, so as to avoid seed glumes. Injuries can alleviate the condition.