How to prevent and control sheath blight in water bamboo? A full analysis of practical methods
Sheath blight in water bamboo occurs in planting areas across the country. As its planting area continues to increase, the disease has become increasingly serious. Sheath blight damages the photosynthesis of water bamboo, causing weak root absorption capacity, and in severe cases it can also cause water bamboo to rot and lodge. So how should sheath blight in water bamboo be prevented and controlled? Let's take a look together.
1. Symptoms
Sheath blight mainly harms the leaf sheaths of water bamboo, followed by the leaves. It is most likely to occur during the tillering stage and the pod-setting stage. It first appears on the leaf sheaths near the water surface, initially as dark green water-soaked spots, or gradually expands into round to elliptical lesions. The center of the lesion is light brown to grayish white, and dark green when humidity is high, while the edge of the lesion is dark brown. Later, multiple lesions overlap each other to form large tiger-stripe-like spots. The lesions extend from bottom to top to the leaves, causing lesions to appear on the leaves as well. In severe cases, they cause the leaf sheaths to turn brown and rot, causing the leaves to yellow and die prematurely. In humid environments, the lesions produce white spiderweb-like threads, which gradually entangle into cotton-like masses and gradually spread into sclerotia the size of rapeseeds.
2. Occurrence patterns
After harvest, the sclerotia fall into the field to overwinter, and these are the main source of inoculum for disease onset the following year. A small number of mycelia and sclerotia overwinter on diseased residues and weeds. Sclerotia left on the soil can survive for 1-2 years and spread by water flow the next year. When the field is in a high-temperature and high-humidity environment, this disease is very likely to occur. Moreover, fields with long-term deep irrigation have severe disease, while shallow water with frequent irrigation and alternating dry and wet conditions are favorable for the growth of water bamboo, so the disease is relatively mild. In addition, the amount and timing of fertilization also have a certain effect on the occurrence and development of this disease. Applying excessive nitrogen fertilizer in the late growth stage will cause the plants to remain green and grow excessively, resulting in a closed field canopy and increased humidity, thus creating favorable conditions for pathogen invasion and worsening the disease.
3. Control methods
The most effective and simplest method to control sheath blight is to implement a rotation of paddy and dryland crops for more than 3 years. Before planting, the source of inoculum should be removed. After irrigation in spring or after plowing and leveling, a gauze bag can be used to collect floating debris mixed with sclerotia from the field edges and corners in the downwind direction, then take it out of the field to burn or bury deeply. This can effectively reduce the source of inoculum, reduce the harm of sclerotia, and lower the incidence rate. At the same time, apply sufficient basal fertilizer, increase the application of decomposed organic fertilizer, appropriately increase phosphorus and potassium fertilizer, and avoid applying too much nitrogen fertilizer. During cultivation, maintain rational close planting, promptly remove old leaves, yellow leaves, and diseased leaves, and improve field ventilation and light penetration. In the early stage of disease onset, fungicides such as carbendazim, wenkujing, and thiophanate-methyl can be sprayed for control. The spray should be uniform and the dosage should be sufficient. An appropriate amount of washing powder can also be added to the spray solution, which helps the solution adhere to the water bamboo plants.
The above is an introduction to the control methods for sheath blight in water bamboo. We hope it can help you. To learn more related knowledge, please stay tuned to us.