More rain, easy to induce rice blight, will not control the reduction of production by 30%
Recently, farmers and friends reacted. The rice was green and oily for a while, and the leaves were yellow and rooted in a few days. By consulting experts, these symptoms in rice are likely to be caused by red wilt. In the recent rainy days, if the field water and fertilizer management is improper, it is very likely to cause the occurrence of red wilt.
Understanding rice blight
Rapeseed is commonly known as rust rice, which is a physiological disease of rice, which mainly affects the normal growth and development of rice. The growth period is delayed, the tiller is reduced, and the small grains are small. Generally, the yield is reduced by 10-20%, and the seriousness is more than 30%.
The disease generally occurs more than the beginning of rice tillering, and reaches the peak of the disease at the peak of tillering.
The affected plants are short, small and small, and the upper leaves are straight and the angle between the stems is small.
After the rice plant enters the tillering stage, brown spots or short streaks appear on the old leaves, the edges are not obvious, and there is a scorching down from the leaf edge along the leaf edge.
At the peak of the tillering stage, clastic brown spots appear on the leaves, and further irregular shapes. Later, the spots increase and expand, and the leaves gradually turn yellow and brown from the base of the leaves. When the disease is serious, the rice leaves in the field are burning. Focal.
When the diseased plant is pulled up, the roots are aging, russet, soft and inelastic, and some become black, rot, and the white roots are extremely small.
The occurrence of rice brown blight
Red blight is the result of a combination of various factors such as soil environment and cultivation management. The main cause of the disease is potassium deficiency in rice plants. During the tillering period, the temperature is low and the rainfall is low. The long-term low temperature and low temperature cause the rice field water temperature, the soil temperature is low, the root system is poorly developed, and the ability of rice to absorb potassium and other nutrient elements is reduced, and the brown blight is induced. From the point of view of the cause, it is divided into the following types.
Soil potassium deficiency
Because the soil itself has a low effective potassium content, it cannot meet the needs of rice growth for potassium. This type occurs mostly in shallow sand fields, water leakage fields and red and yellow soil paddy fields. This kind of field often begins to develop after ten days of rice planting. The leaves of the initial rice plants are slightly dark green, the leaves are long and soft, and the leaves of the base gradually turn yellow or yellowish brown from the tip of the leaf edge along the leaf edge. Typical symptoms are transparent, with less root hair and easy to fall off.
Plant poisoning
Because the soil contains a large amount of reducing chemicals such as ferrous iron, hydrogen sulfide and other toxic rice roots, reducing its vitality and disease. This type occurs mostly in deep mud fields, long-term deep water, poor ventilation, and fields where excessive amounts of unfertilized organic fertilizer are applied. This kind of rice seedlings is difficult to return to green after planting, or the rice seedlings stand upright after greening, almost no tillering, the tip of the leaves first fading down, the leaves of the leaves are yellowing around, and they grow reddish-brown dark spots, even rot, similar to rotten eggs. The smell.
Low temperature induced type
Long-term low temperature and rain affect the development of rice roots, leading to a decline in the ability to absorb fertilizer. This type occurs mostly in the early rainy season or the rainy season in the early stage of rice growth, and the large area is simultaneously ill, but the degree is light and heavy. Because under the low temperature conditions, the upper leaves of the plant turned pale yellow, and many brown needle-like small spots appeared on the leaves, especially the tip of the leaves. The lower old leaves were initially yellow-green or light brown, followed by typical symptoms. Rice roots are soft, less elastic, and have fewer white roots. In addition, seedlings planted deep, partial nitrogen fertilizer, long-term water accumulation in rice fields, etc., will increase the occurrence of rice brown blight.
Prevention and cure method of rice brown blight
Red blight must adhere to comprehensive prevention and control, mainly to prevent, the affected field should take corresponding measures according to different types of occurrence, targeted prevention and control.
1. Intensive cultivation and improvement of soil. By deepening the tillage layer, promoting soil ripening, avoiding continuous no-tillage and interplanting; renovating low-yield fields, renovating the soil and remediating irrigation and drainage systems for poorly drained muddy fields; timely ploughing and drying after harvesting, and improving soil ripening Degree to improve soil permeability.
2. Strengthen cultivation management to improve disease resistance of plants. Timely planting, strengthen water slurry management, shallow water live tree, promote early development; balance fertilization, apply more decomposed organic fertilizer, increase phosphorus and potassium fertilizer, alternate dry and wet, timely lay-up, cultivate strong seedling; straw returning field, The amount of base fertilizer should be appropriately increased. The ratio of base and manure is adjusted to 6:4. Nitrogen should be appropriately moved forward to accelerate the decay of straw, strengthen the management of water layers, regulate water with water, and adjust fertilizer with water.
3. Strengthen classification guidance to control the onset early. For the potassium-deficient field, the potassium fertilizer should be supplemented and the quick-acting nitrogen fertilizer should be properly applied; the fermented field with excessive organic matter should be drained immediately; during low temperature and rain, it should be drained in time, and the wet and dry alternate management should be carried out to prevent long-term deep irrigation. For the diseased field:
1 Appropriate application of potassium fertilizer (about 7.5kg/mu) to prevent partial application of nitrogen fertilizer;
2 Appropriate exposure, adhere to the “shallow-wet-dry†water slurry management mode, dehydrate the exposed fields, increase soil aeration, increase root activity, promote new roots, and improve the potassium absorption capacity of roots;
3 Spray the foliar fertilizer, and spray the growth regulator such as potassium dihydrogen phosphate solution on the affected field in the evening to promote the rapid transformation of the seedlings.
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