How to control rice panicle neck blast caused by white panicle or deflated grain

Rice panicle neck blast is a common and airflow disease in rice. When the rice growth is about to enter the broken heading stage and the rice flowering and filling stage, the panicle neck blast is easy to occur when the rainfall is too large before and after heading. After infection, the neck node of the panicle was necrotic, and the channel of nutrient transport was blocked, forming white spikes or shrunken grains of rice ears. In the year in which panicle neck blast occurred, the yield was reduced by 1020%, serious fields were more than 30%, or even no harvest. Once the panicle neck of rice is infected with rice blast, it will greatly affect the yield and quality of rice.

Rice panicle neck blast

1. Harmful symptoms: panicle neck rice blast mainly occurs on rice panicle neck or rachis. Ear neck disease, the disease spot brown or gray-black, gradually expanded, can be as long as 3-4 years. When the disease is early and serious, it causes white ear; when the disease is late, when the disease is mild, the 1000-grain weight decreases or blighted grain. Panicle neck blast often causes rice panicle stem breakage, and the symptoms on rachis branches, branches and regenerated branches are similar to those in panicle neck, but only spikelets are damaged and spikelets are unfruitful.

Second, occurrence regularity: Rice panicle neck blast spreads quickly with the help of airflow, which is related to climate, variety, fertilizer and water management, physiological variety variation of pathogen and so on.

1. Climatic conditions: low temperature, more Rain Water, high humidity, less sunshine, sunny and rainy, foggy and dewy, which is beneficial to the occurrence of neck blast. The daily average temperature is 2428 ℃ and the humidity is more than 90%. It is easy to be popular. At heading stage, rice is easy to induce neck blast when it is cold and rainy for 3-5 days.

2. Variety resistance: the resistance of rice varieties to rice blast is relative and not absolute. The resistance of the same rice variety is different in different growth stages, and it is susceptible to disease at tillering stage and heading stage. Planting a single rice variety in a continuous large area is also easy to induce rice blast.

3. Cultivation conditions: transplanting rice seedlings too late, high density, insufficient light in the field, poor ventilation, too much nitrogen fertilizer, too late, so that the field growth is exuberant, greedy green late maturity, ineffective tillers increased, irregular heading, promoting the development and spread of the disease. Long-term deep water irrigation or drought.

Rice control

3. Control methods: according to the occurrence characteristics of rice panicle neck blast, the control method of "prevention first and comprehensive control" should be adopted.

1. For reasonable collocation of disease-resistant varieties, two or more varieties should be planted on the same plot, and varieties should be replaced in different years.

2. Reduce pathogens and disinfect seeds. Soak the seeds with prochloraz and other agents for 2-3 days and stir once every morning and evening.

3. Properly deal with diseased straw and reduce the source of primary infection as much as possible.

4. do a good job of fertilizer and water management, increase the application of organic fertilizer, and control the amount of nitrogen fertilizer. The general rice varieties in our region need 130 kg of pure nitrogen, 50 kg of pure phosphorus, 75 kg of pure potassium and 25 kg of zinc fertilizer per hectare. Around July 5, 30% pure nitrogen and 40% pure potassium were applied as panicle fertilizer. Before and after heading, rice leaves yellowed and 10% pure nitrogen was applied as grain fertilizer. The principle of "light before, in the sun and wet after" should be carried out with water. During the whole growth period, the irrigation depth is below 3cm, but if it is less than 17 degrees in mid-late July, deep-water irrigation should be more than 20cm to reduce chilling injury.

5. From late July to early August, emphasis was placed on the prevention of panicle neck blast. At the initial heading stage of rice, about 5% of the rice in the field was prevented by applying pesticide once at heading stage, and again at full heading stage.

6. Prevention and control agents: 40% Fuji No. 1, 40% gram distemper powder, 75% diazepam and other agents.