Control techniques of false smut in Rice

Rice false smut is a kind of rice disease with a wide range of harm, which occurs in the main rice producing areas in the world, and the north and south rice in China are affected by it. After the occurrence of rice false smut, rice mildew will occur and the hollow rate will increase, which will affect the rice quality, reduce the commodity value and affect human health. So how to prevent and cure it?

Control methods of false smut in Rice

The main results are as follows: 1. The varieties with high yield and disease resistance are selected: the disease is lighter in general loose panicle type and early maturing variety, and more serious in dense panicle type and late mature variety. For example, new varieties Chujing 28 and Yunjing 26 are selected.

2. removal of diseased bodies: when diseased grains are found in the early stage, the seriously diseased fields should be removed in time, and the seriously diseased fields should be turned over deeply after harvest, so that sclerotia and curved balls can rot in the soil. Before sowing in spring, clean up the debris in the field to reduce the source of bacteria.

3. Scientific and rational fertilization: farm manure and organic fertilizer should be the main fertilization conditions in the field, nitrogen, phosphorus and potassium fertilizer should be used together, and nitrogen fertilizer should not be applied too late.

4. Scientific water management: scientific water management is carried out in the field according to the characteristics of water demand for rice growth, that is, planting seedlings in shallow water, turning green in an inch of water, tillering in thin water, cool enough to sun the field, promoting ears in an inch of water, and moisturizing strong seeds.

5. Chemical control: 40% Sclerotinia sclerotiorum 100 g or 20% Jingangmycin 100 g and 60 kg water were sprayed evenly to control rice false smut twice in 7-10 days before heading (round bract stage) and full heading stage.

What is rice false smut?

Rice false smut is an important disease that occurs in the panicle of rice in the later stage of rice growth. the disease often occurs in the year of good rice harvest, and is often mistaken by farmers as a sign of harvest and called "bumper harvest". Rice false smut is mainly susceptible to rice false smut at heading and flowering stage. the pathogen is harmful to part of the grain on the panicle, usually with one to several grains on a panicle, and more than a dozen grains in severe cases.

The yellowish green mass appeared at the suture of Yinggu, gradually expanded, and finally wrapped in the whole glume shell, the shape was 4 times larger than that of Jian Gu, it was dark green, smooth, cracked and cracked, and scattered dark green powder, that is, thick chlamydospores of the pathogen.

Rice false smut not only destroys the diseased grains, but also consumes the nutrition of the whole diseased ear, making other grains not full. With the increase of diseased grains, empty chaff grains obviously increase, 1000-grain weight decreases, resulting in a serious decline in rice quality. Rice false smut toxins pollute rice, which can cause poisoning and seriously harm the health of human beings and animals. In recent years, rice false smut occurred in varying degrees in Hongta district due to the increase of planting area of high-quality rice and the continuous overcast and rain at heading and flowering stage.

Harmful symptoms of false smut in rice

Rice false smut is a fungal disease, which occurs only in panicles. After the pathogen invaded the grain, the mycelium was formed in the glume, and after destroying the internal tissue of the diseased grain, the mycelium increased gradually. At first, the yellowish green spore seat was exposed from the suture of the inner and outer glume, and then changed into dark green or olive color, which wrapped the glume, which was nearly spherical and could reach several times the size of healthy grains. Finally, the surface of the sporangium cracked and scattered dark green powdery chlamydospores.

Dissecting the diseased grain, the center is a white fleshy mass composed of mycelium tissue, and the periphery can be divided into three layers: the outer layer is the earliest mature chlamydospore, dark green; the middle is the hyphae and gradually mature chlamydospore, orange-yellow; the inner layer is radial hyphae and forming chlamydospores, light yellow. In the later stage of the disease, there were 2-4 black, slightly flat and hard sclerotia on both sides of some sporangia. Sclerotia are easy to fall off in the field for overwintering.

Causes of false smut in Rice

The prevalence of rice false smut is mainly determined by the number of sclerotia in the field, the pathogenicity of varieties, the coincidence between rice heading stage and sclerotia germination, the coincidence degree of spore transmission stage, the rain-humidity coefficient of heading stage and so on.

1. Host resistance: there were significant differences in resistance and susceptibility among varieties under natural conditions, and varieties with late heading tended to occur greatly. the disease of japonica rice was more serious than that of indica rice, and that of hybrid rice was heavier than that of conventional rice. The occurrence of diseased grains was mainly in the middle and lower part of the ear, followed by the upper part, and the large panicle and dense panicle varieties with more stalk grains had high incidence. The varieties with slow heading rate and long heading period also had a long time of disease and serious disease.

2. Environment: heavy rain and low temperature, especially continuous rain, occur heavily during heading and flowering. In the flowering stage of rice, the daily average temperature is 25-28 ℃, and there are 3-5 days of continuous rain, which is easy to induce the disease.

3. Cultivation: because of the large amount of bacteria in the seeds of the fields with serious disease in ① in the same year, the disease may be serious in the second year.

The excessive application of nitrogen fertilizer and panicle fertilizer in ② and the absence of phosphorus and potassium fertilizer will lead to serious field cover, poor ventilation and light transmission and high relative humidity, which will aggravate the occurrence of the disease.

③ flooding, series irrigation and flood irrigation are important reasons for the spread of rice false smut. Near the mouth of the water, the edge of the field, and improper field management, the late fall into the water too late, the disease is serious.

The above editors have introduced rice false smut to you, and we have learned about the causes and control methods of rice false smut. In order to ensure the harvest of rice, we must pay attention to preventing the occurrence of some diseases and insect pests, and we must constantly learn techniques in order to achieve high and high yields. Here, the editor also wishes you all a good harvest.