Main diseases of rice at seedling stage

Rice seedlings need to do a good job of disease control in order to ensure the later growth and produce high-quality rice ears. What are the main diseases of rice at seedling stage? How to prevent and cure it?

1. Main diseases of rice at seedling stage

1. Evil seedling disease

The diseased seedlings of rice at seedling stage were slender and taller than healthy seedlings, the leaf sheath was slender, the leaf color was yellowish, the root system was poorly developed, and some of the diseased seedlings died before transplanting. There are light red or white mildew powder on the dead seedlings, the internodes are obviously elongated, the nodes are often curved and exposed outside the leaf sheath, and most of the lower stem nodes are inversely adventitious with few or no tillers. Peel off the leaf sheath, there are dark brown spots on the stem, cut open the diseased stem to see white arachnoid hyphae, and then the plant gradually withered. When the humidity is high, the surface of the withered and diseased plant is covered with light brown or white powdery mildew, and the black dot in the later stage is the pathogen capsule.

2. Bacterial wilt

There are two kinds of rice bacterial wilt, one is physiological bacterial wilt in rice seedling stage, the occurrence is more common, often mixed with bacterial wilt. The symptom is that the aboveground part of rice is rapidly dehydrated and withered, and the seedlings are still green when they die; the other is the bacterial basic rot that occurred in the later stage of Honda, which occurred sporadically in the field, even only 1-2 plants in a cluster. The basal stem nodes of the diseased plants were hard, blackened and stinky. Physiological bacterial wilt mostly occurred before and after the 3-leaf stage of rice. It is mainly due to low temperature chilling injury, sudden sunshine after cold or excessive temperature difference, for example, there is no timely ventilation before the rice seedling field is exposed, which causes the seedlings to grow excessively, and after the film is removed, the seedlings can not adapt to the environment, resulting in the imbalance of water supply in the seedling body, which causes the aboveground part to lose water quickly and die.

3. Blight

Rice blight is a Pythium of flagellum subphylum. The pathogen overwintered in the soil, and after rice sowing, the pathogen began to invade the seedling, and the disease of the seedling was the most serious under the condition of lack of water. The disease often occurs in rice dry nursery field, and it is a common and major disease in rice dry seedling field. The symptom is that after the second leaf stage of the seedling, the leaf tip withered and atrophied, the root hair was sparse, and the initial stage occurred in clusters on the seedling bed. After the fourth leaf stage, the disease symptom was sudden green wilt, and the seedling leaves rolled and wilted in clusters, and then withered. Low temperature, overcast and rain and lack of light are important conditions to induce blight, among which low temperature is the most important. The disease resistance of seedlings decreased under the condition of low temperature, which was beneficial to the occurrence of disease. Such as continuous low temperature or sunny after overcast and rain, insufficient soil moisture, physiological imbalance of seedlings and aggravation of diseases.

4. Seedling rice blast

Rice seedling blast is a disease caused by seed-borne bacteria and diseased rice straw. seedling rice blast begins to occur after the seedling three-leaf stage. The symptom is that the base of the diseased seedling is gray-black, the upper part turns brown, curls up and dies, and a large amount of gray-black mildew layer is produced in the disease part when the humidity is high. The pathogenic factors are beneficial to the disease in the presence of rain, fog and dew. When the temperature is 20 ℃-30 ℃, especially in 24 ℃-28 ℃, when there are more rainy days and relative humidity is more than 90%, it is easy to cause serious occurrence of rice blast.

II. Control of Rice Seedling Diseases

1. Prevention and control methods of evil seedling disease.

In the rice seedling 1-2 leaf stage, use Qingku Rick 50ml + garlic oil 15ml, spray 15kg of water, once every 5-7 days, even spray twice, can also spray 95% Luheng No. 1 (carbendazim) for control.

2. Control methods of bacterial wilt.

The prevention and control of bacterial wilt is to ventilate the seedlings in time after the seedlings are ready, except in windy days. In the paddy seedling field, the seedlings should be protected by adjusting the water layer before the strong wind drops the temperature. 15% Likujing can be used for chemical control, 100 grams per mu of seedling field, 50 kg-60 kg of water, sprayed twice after 3 o'clock in the afternoon on a sunny day, once every 7 days, or 1.5 kg of 65% dimethazone wettable powder, or 2 kg of carbendazim and 60 kg of water.

3. Control methods of blight.

The growth of seedlings should be checked in time after low temperature, overcast and rain, and when it is found that there is no spitting water at the leaf tip of the seedling or when the seedling is abnormal, it should be sprayed on the seedling bed with 25% metalaxyl wettable powder according to 0.75 grams per square meter or 58% metalaxyl manganese-zinc wettable powder according to 1 gram per square meter and 2 to 2.5 kilograms of water.

4. Seedling rice blast

Prevention of seedling rice blast disease is generally after the seedling three-leaf stage, choose 40% thiocyclazole, 150 grams per mu, 50 kg-60 kg water to prevent twice, once every 7 days. It can also be sprayed or poured with 75% tricyclazole 60g-80g or Fuji No. 1 100ml with 60kg water.

The above are several diseases and control methods that may appear in the rice seedling stage. I hope it will be helpful to you. If you have any questions, please consult the relevant personnel.