Causes of Rice Bad Seedling Disease

Rice evil seedling disease is a major disease in the process of rice planting, the emergence of the disease can often lead to a 10-20% reduction in rice yield, and in serious cases, it can be reduced by half, so it is urgent to find the cause and prevent it. What is the cause of rice evil seedling disease? How to prevent and cure?

I. what is Rice Bad Seedling Disease

Rice evil seedling disease, also known as overgrowth disease and white stem disease, is a fungal disease, which can occur from seedling stage to heading stage, and the peak of disease is in seedling stage, field stage and heading stage. Among them, rice is the most susceptible to disease at seedling stage.

Due to the poor root system, the growth of the diseased seedlings was slender and thin, the whole plant was yellowish green, which was nearly 1 inch higher than that of the healthy plants, and the leaves were narrower. Most of the diseased plants died before transplanting, and a few of the diseased plants died within 25 days after transplanting. When the air humidity is high, the reddish or white mildew is sometimes produced in the dead seedling near the ground, that is, the conidia of the pathogen. The degree of disease in rice seedling stage is related to seed-borne bacteria.

Second, the cause of rice evil seedling disease.

The main results are as follows: 1. The main source of primary infection of rice evil seedling disease is infected seeds, followed by diseased rice straw. After seed germination, the pathogen invades from the bud sheath, root and root cap or wound of the seedling, and the wound of the plant is conducive to the invasion of the germ, which will cause the disease of the seedling to grow; after transplanting the diseased seedling, it will cause the disease of the rice seedling; at the same time, the conidia produced by the diseased plant can be re-infected with the help of air flow, so that the grain and rice straw can be infected again, forming cyclic infection and harming rice.

2. High temperature creates conditions for the occurrence of rice evil seedling disease. The pathogen of this disease likes high temperature, which is very beneficial to the reproduction, infection and occurrence of rice pathogen. The most diseased seedlings appeared when the soil temperature was 30-35 ℃, and less at 25 ℃. When the seeds and seedlings were injured, it was beneficial to the invasion of pathogens.

3. Under the same conditions, the carrier rate of seeds was extremely high, and there were significant differences among varieties. The disease of japonica rice was significantly more serious than that of indica rice, and the average diseased plant rate of different varieties was between 0.07% and 2.8%.

4. The pathogen of rice evil seedling disease belongs to ascomycetes. On the one hand, the conidia on the infected seeds polluted the disease-free seeds before sowing, on the other hand, the mechanization of rice harvesting was very high, and the straw returned to the field after harvest could not only improve the soil fertility, but also increase the accumulation of pathogens in the field and seeds.

5. the occurrence of evil seedling disease of dry-raised seedlings is more serious than that of water-raised seedlings.

6. Improper seed is caused by not operating in accordance with technical standards, and insufficient seed soaking concentration will affect the efficacy, and the result can only aggravate the occurrence of evil seedling disease in the field.

Third, how to control rice evil seedling disease

The main results are as follows: 1. First of all, it is the most effective and reliable method to establish disease-free field, select disease-resistant varieties, select healthy and disease-free seeds, and weed out injured and blighted grain seeds. Secondly, doing a good job of seed disinfection is the key to disease prevention. Before disinfection, the rice seeds should be sunny for 1-3 days, soak the seeds with 80% strong chlorine 300 times solution, the control effect can reach 98%, late rice soaked for 12 hours, early rice soaked for 24 hours, and then soaked in clean water. Soak the seeds with 3% quicklime water clarification solution for 2 days at 25 ℃ to avoid direct light. The liquid level should be 10-15cm higher than the seed, which is beneficial for the seed to absorb the liquid. The liquid level should be kept at rest and cannot be stirred halfway to ensure that the bacteria will suffocate.

2. The sprouting should not be too long before sowing, otherwise the plant is vulnerable to trauma when sowing, which is beneficial to the soaking of pathogens; when transplanting and pulling seedlings, we should avoid damaging the seedling roots as far as possible to prevent root dysplasia, so as to reduce the incidence of evil seedling disease; avoid high temperature weather and noon when transplanting seedlings, do not transplant hot sun seedlings, high temperature is the most suitable condition for the occurrence of evil seedling disease.

3. Once the infected plants are found, they should be pulled out in time. The diseased plant is 1 stroke 3 higher than the normal seedling, so it is easy to identify. Focus on burning after removal, so as to avoid re-infection.

4. Diseased straw can be used as fuel or high temperature retting to compost after harvest.

A good understanding of the causes and conditions of the disease and relevant prevention and treatment measures can greatly reduce the incidence.