Detailed Explanation of the Causes and Control Techniques of Rice Bacterial Leaf Blight
The pathogen of rice bacterial leaf blight is Xanthomonas oryzae, a bacterium belonging to the genus Xanthomonas. Bacterial leaf blight is one of the major diseases of rice. Once it occurs, it generally reduces yield by 10%, and in severe cases by 50-60%. Therefore, strengthening the control of bacterial leaf blight is very important. 1. Causes of the disease 1.1 Relationship between disease occurrence and climatic conditions...
The pathogen of rice bacterial leaf blight is Xanthomonas oryzae, a bacterium belonging to the genus Xanthomonas. Bacterial leaf blight is one of the major diseases of rice. Once it occurs, it generally reduces yield by 10%, and in severe cases by 50-60%. Therefore, strengthening the control of bacterial leaf blight is very important.
1. Causes of the disease
1.1 Relationship between disease occurrence and climatic conditions
High temperature, high humidity, and strong winds with heavy rain are the climatic conditions for bacterial leaf blight epidemics. In the field, the disease begins to occur when the air temperature reaches 17°C, with the peak period of occurrence at 26-30°C, a short incubation period, and only about 3-5 days from pathogen invasion to symptom appearance, with an increase in the number of reinfections. Continuous low temperatures below 17°C and high temperatures above 35°C do not cause disease occurrence. A relative humidity above 90% is favorable for the pathogen to infect the host.
1.2 Relationship between disease occurrence and varietal disease resistance and growth stage
There are certain differences in resistance to bacterial leaf blight among rice varieties. Generally, glutinous rice is the most resistant, japonica rice is more resistant than indica rice, tall-stemmed narrow-leaf varieties are more resistant than short-stemmed broad-leaf varieties, fertilizer-tolerant varieties are more resistant than non-fertilizer-tolerant varieties, and varieties with fewer leaf surface stomata are more resistant than those with more leaf surface stomata, while planting susceptible varieties makes epidemics and disasters more likely. The same variety is relatively resistant from the seedling stage to the tillering stage, resistance declines at the late tillering stage, it is susceptible at the booting stage, and most susceptible at the heading stage.
1.3 Relationship between disease occurrence and cultivation techniques
Whenever nitrogen fertilizer is applied excessively, too late, or too concentrated, especially when panicle fertilizer is applied improperly, causing the plants to grow excessively, dense shading between rows and plants, poor ventilation and light penetration, and leaves that are dark green and tender, the disease resistance of the plants will weaken. Flooded plants develop more severe disease than non-flooded plants. Continuous irrigation and flooding irrigation in the field can directly promote the spread of the disease, and rice plants soaked in deep water for a long time are affected even more, mainly because the high field humidity is favorable for pathogen reproduction and infection; deep irrigation can also increase the accumulation of toxic substances in the soil, causing the disease resistance of rice plants to decline, and deep irrigation after the jointing stage causes even more severe disease.
2. Control techniques
2.1 Select disease-free seeds.
2.2 Scientific management
In the field, apply sufficient basal fertilizer, topdress early, skillfully apply panicle fertilizer, do not apply nitrogen fertilizer in a biased manner, and apply nitrogen, phosphorus, potassium, and micronutrient fertilizers in a balanced way. Strictly prevent large water volumes from submerging the seedlings, cultivate high-quality strong seedlings, and advocate dry seedling raising. The field should be irrigated frequently with shallow water, alternating dry and wet, and dried and wet alternately, and the field should be sun-dried at the appropriate time and to an appropriate degree. For fields that have already developed the disease, heavy sun-drying is also not suitable, so as to avoid worsening the disease.
2.3 Timely control
When applying pesticides in the field, follow the principle of "treat a patch when there is a spot, treat a block when there is a patch," and spray pesticide in time to seal off the disease center. If the climate is favorable for disease occurrence, general survey and control should be carried out in similar fields, thereby controlling the spread of the disease. In areas where bacterial leaf blight occurs frequently, use Yekuning for prevention at the booting stage. For fields submerged by water and fields hit by storms, after the water recedes and the weather clears, promptly use 100 grams of Yekuning per mu mixed with 60 kg of water for uniform fine mist spraying for prevention. In the early stage of bacterial leaf blight, generally every 5-7 days, use 100 grams of Yekuning per mu mixed with 60 kg of water for uniform fine mist spraying for control once, for 2-3 consecutive times, which can reduce and lower the losses caused by the occurrence of bacterial leaf blight.