Now that early rice has entered the period of young panicle development, the weather is changeable, and thundery weather, high temperature and high humidity can easily cause the occurrence of rice sheath blight, and it is also the high incidence period of S. japonica, rice leaf roller, and rice planthopper. The prevention of pests during the earing period is particularly important for capturing the early rice harvest. The symptoms, pathology and control methods of the two diseases of sheath blight and rice planthopper are briefly summarized as follows:
Sheath blight
Analysis of Causes: The main source of primary infections was mainly the sclerotia in winter and sclerotia in the soil, and the hyphae on the side of the field and the weeds in the ditch. Therefore, the amount of sclerotia in the soil is the basis for the severity of rice sheath blight. The main reasons affecting the amount of sclerotia in the soil are as follows: First, it is difficult to turn rot sclerotium in the soil. After the conversion of paddy fields into dry land, the land is difficult to cultivate, the dry crop yield is not high, and the efficiency is not good. Therefore, rice growers are reluctant to crop, resulting in continuous cropping of rice. The amount of bacteria causing the disease in the soil accumulates year by year, accumulating and accumulating. The second is that the treatment of field diseases is not thorough. In the survey, it was found that most of the rice straw was removed from the field due to continuous cropping of rice but it was not completely removed. The diseased straw was left in the field without sterilizing and maturing, which not only caused the accumulation of bacteria, but also increased the incidence. At the same time, it has also become an important starting point for new occurrence and spread of rice sheath blight.
Prevention and control measures: Based on agricultural prevention and control, good management of fertilizers and waters should be carried out to improve the environmental conditions for rice growth, and to protect early-stage use of drugs that are severely affected by the past years. 1. Agricultural control methods: 1 Remove sclerotia. During the irrigation process, the "slag" floating on the surface of the water is salvaged, and the nucleus is sterilized. To facilitate thorough salvage, the field should be leveled and deeper. 2 shallow water irrigation, timely field. In general, shallow water is poured before the flood season, and the field is dried at the end of the tillering season. After the booting season, dry and wet, wet and dry alternately, wet and dry alternately, shallow water ground irrigation to reduce the field humidity, control the invalid tiller, prevent premature closure, reduce the incidence of disease. 3 Reasonable fertilization. Organic fertilizers should be applied more, phosphorus and potassium fertilizers should be added, and the plants' resistance to disease and lodging should be enhanced. The fertilization should be done in the early stage, but it should be closed early, and it should not be greedy or late in the later period. It can not only produce high yields, but also control diseases. 2. Chemical control: When the incidence of rice tussock reaches 20%, it can be used as an indicator for pesticide control. The time of application is appropriate before and after heading. High-fertilizer blocks should be used before closure of the line. 15 days to prevent and treat 1-2 times. The main pharmaceuticals are 15%, 25% Jinggangmycin 25-40g/mu, or 25% Propiconazole EC 15-300g water 60-100kg/mu spray. When spraying, ensure that the amount of medication is used. Spray the liquid on the lower part of the plant and apply it in the morning with dew to increase the control effect.
Rice Leaf Roller
Rice leaf roller, commonly known as leaf roller leafworm, is an important pest that injure rice. In addition to damaging rice, it also harms grassy weeds such as wheat and sugarcane. 1. The main characteristics of the occurrence: 1 adults: adults of rice leaffolders have phototaxis, hi shade and damp, and can move long distances. Every spring, adults come from the south to the north with the monsoon, and fall down with the air sinking and rain towing, becoming the initial insect source in non-wintering areas. In the fall, adults relocate with the monsoon to the south for breeding, wintering with larvae and cockroaches. 2 eggs: prolific in the back of the leaves, 3-5 were arranged in fish scales, a few yields. 3 larvae: not very lively, very few leaves turning. The 2nd instar larvae can roll the leaf tip into small insects, and then the leaf filaments can form new insects in the rice leaves. The larvae hide inside the insects and feed. After 3rd instar, the food intake increases, the insects inflate, enter the gluttony period, and turn frequently. Infestation of the larvae, the fourth and fifth instar larvae eat about 95% of the total intake.
2. Control measures: 1 Agricultural control: The use of resistant (resistant) rice varieties, reasonable fertilization, so that the growth and development of rice robust, to prevent prosperous early, later love Qingshu late. Scientific management of water, proper adjustment of the time of field pruning, reduce the field humidity of the larvae during hatching, the local insect source in the phlegm peak irrigation period of 2-3 days, kill the insects. 2 Chemical control: According to the damage characteristics of rice leaffolders, especially the characteristics of greater loss during the ear period, the strategy of chemical control shall be based on the principle of the generation of victims at the heading stage, and the principle of severe disinfaction at the end of delivery. The period of pesticide application for control of rice leaf roller should be determined according to the length of the different pesticide residues and the sensitivity of larvae. When hatching, use bio-pesticides with short-lived effect and apply pesticides 1-2 days after the peak of hatching. Inappropriate larvae should use pesticides that are sensitive to older larvae and have a long-lasting effect. Apply pesticides at the peak of incubation, but in actual production, Should be based on the actual, combined with the control of other pests and diseases, flexible control.
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